We are used to thinking that the entire Jewish people - except for a small number of converts who have assimilated in over the generations - share a common family background of slavery in Egypt and acceptance of the Torah at Sinai. I would like to suggest, following the lead of R' Yoel Bin Nun and R' Yaakov Medan, that there were two major exceptions to this rule.
1) Thousands of Israelites from the tribes of Efraim and Menashe had already settled in Israel before everyone else left Egypt.
2) Thousands of people, whose ancestors had followed Avraham from Mesopotamia, settled in Yaakov's time in the Shechem region (modern Nablus, northern West Bank), and remained there for hundreds of years afterwards.
Both groups met up with the main Jewish people (under Moshe and Yehoshua's leadership respectively), agreed to a covenant, and effectively became Jews from then on.
The story of these two groups is not explicit in Tanach. That is of course the main obstacle to believing that it occurred. But it solves a large number of textual difficulties which span every historical book in Tanach. Some are minor or can be explained in other ways, but others are very serious. Given the breadth of the evidence, I think the question is not whether the story of these two groups occurred, but rather, why Tanach did not see it fit to tell the story explicitly.
If you don't have patience to read all the textual evidence for the story, then skip to the end, where (among other thoughts) I try to answer the question of why the story is not explicit.
2) AVRAHAM'S FOLLOWERS
WHERE DID THEY GO?
Avraham generally sounds like a solitary guy, but in fact he was accompanied by thousands of followers. He took an indefinite number of people with him when he made aliyah. (Breishit 12:5 might indicate that they were his slaves; the midrash says they were converts to proto-Judaism. These two suggestions might be reconciled through the later halacha that an "eved kenaani" must effectively convert to Judaism.) The 318 warriors he uses to defeat Chedarlaomer's army (Breishit 14:14) must have had families, and not every man is a warrior, so the overall number must have been in the thousands. What happened to these people, who were loyal enough to follow Avraham from Mesopotamia? Did they just disappear, or abandon him and assimilate with the Canaanites?
Perhaps they and their descendants stayed loyal to Avraham's family, living in Canaan along with Yitzchak and Yaakov. When Yaakov left for Egypt, at least some of them may have remained in Canaan (Breishit 46:5-7 seems to indicate that Yaakov's family left alone, unaccompanied by friends or allies).
"Then Yaakov said unto his household, and to all that were with him: 'Put away the strange gods that are among you, and purify yourselves...' " (Breishit 35:2). Which people were with Yaakov, besides his household? The Torah never tells us.
It makes sense to say that they were the grandchildren of those who had been loyal to Avraham. If Yaakov's own family was suspected of idolatry, his followers would be even more suspect, but nonetheless Yaakov would have influence over them. There is a very similar passage (Yehoshua 24:14) in which Yehoshua tells a crowd assembled at Shechem to abandon their idolatry. It makes sense to say we are talking about the same people (or rather, their descendants). Both events, it should be noted, take place in Shechem.
MY SWORD AND BOW
"Moreover I have given you one portion ["shechem echad"] above thy brethren, which I took out of the hand of the Amorite with my sword and with my bow." (Breishit 48:22) This verse is well-known because it was made into a song, but is hard to explain. What land is Yaakov talking about? When did he ever conquer land in Israel? There is the well-known story of Dinah and Shechem, but that massacre was carried out by Shimon and Levi, not Yaakov, and was condemned by Yaakov. Why would he take credit for it now? Some commentators use it as an explanation, but it is very difficult. Plus, Shechem was probably a powerful kingdom and could not be conquered by one or two people. Even if the people of one city were massacred quickly, there would have been smaller cities and many villages which escaped.
It is much more reasonable to say that the thousands of followers conquered Shechem, with Yaakov's approval or under his leadership, and then settled there. This apparently occurred independent of, and I would guess before, the Dinah story. The indigenous population was not wiped out - though Shimon and Levi would partially do that later - so Yaakov could be proud of the conquest, though he was embarrassed by Shimon and Levi's actions later on. When it was time to promise Yosef an inheritance, Yaakov decided to promise the area which he and his followers had conquered long before.
Yehoshua 24:12 is very interesting and perhaps related. "And I [God] sent the hornet before you, which drove them out from before you, the two kings of the Amorites [Sichon and Og]; not with thy sword, nor with thy bow." Later on I will argue that the audience of Yehoshua 24 is specifically the descendants of Yaakov's followers. If so, this line seems to be contrasting the almost-miraculous conquest of the east bank with the more normal conquest of the Shechem area centuries before. To make the contrast, Yehoshua alludes to the famous "with my sword and with my bow" line, which Yaakov had used in Breishit 48:22 regarding Shechem, and which would have been familiar with those who had perfomed the conquest.
(It could also be that "sword and bow" is just an idiom for war, or for a specific type of war, in which case this last argument would be weakened. But the phrase "with [one's] sword and with [one's] bow" appears just three times in Tanach: Breishit 48:22, Yehoshua 24:12, and Melachim II 6:22. This is rare enough that you can make a case that, given the probable audience, the second occurrence is alluding to the first. It's possible that the third occurrence refers to the first as well: the context of massacre there is reminiscent of Shimon and Levi's massacre in Shechem.)
I SEEK MY BROTHERS
At the time of Yosef's kidnapping, Yaakov's family had been living in Hevron. And yet when the brothers wanted to graze their flocks, they went all the way north to Shechem, and then to Dotan, which is not far from Shechem (Breishit 37:14-17). If they had to go so far away from home, why specifically to Shechem? And how is it that the random man who Yosef meets in the field near Shechem (37:15) recognizes both Yosef and his brothers?
If Shechem was populated by the thousands of followers, then both questions can easily be answered. The brothers naturally went to the place where they had a family connection. And since Yaakov's family was responsible for the followers' settlement in Shechem, it makes sense that their family would be well-known by at least some of the inhabitants.
In Yehoshua's time, just before the land of Israel was conquered, Shechem ruled a powerful kingdom, and was one of the most powerful Canaanite city-states (this is known from archaelogical records). It is extremely surprising, then, that Shechem is not listed as one of the 31 city-states ("kings") conquered by the Israelites (Yehoshua 12:9-12:24). The locations of most of the 31 are known, and there is a large geographic gap right where Shechem is located. Furthermore, archaeologists in El-Amarna, Egypt have found letters sent from many Canaanite city-states, begging for help against a wave of invaders in Yehoshua's time. Shechem is a conspicuous exception in that it did not ask for help, and it may even have not fought the invaders at all. So why did Shechem get a pass from the Israelites? And why don't we hear about such a large mass of unconquered Canaanites later on?
It seems Shechem cooperated with Yehoshua, and later on converted to Judaism, accounting for the lack of later mention of Canaanite inhabitants. Why this special treatment, when Yehoshua had been commanded to kill all the Canaanites? (When the Givonites were spared because they made a treaty with Yehoshua, this is specifically mentioned, but Shechem is not.) Perhaps the people of Shechem (or at least the leaders) were not Canaanites at all, but the descendants of Avraham's followers, who stayed in the Shechem area after Yaakov's family went to Egypt. When the Israelites returned under Yehoshua, they absorbed these people among them rather than fighting against them.
GERIZIM AND EVAL
Yehoshua's conquest began very methodically: first Jericho (right where the Israelites crossed the Jordan), then Ai (a little further along the main road), then the encounter with Givon (close to Ai), then the battle south and west of Givon. But right in the middle of this sequence (Yehoshua 8:30-35) the Israelites visit Har Gerizim and Har Eval (the mountains on either side of the city Shechem) and perform various ceremonies there. It is very strange that they would go so far out of their way, and that they were not molested by hostile Canaanites from the Shechem area, just when the kings of the south were gathering a coalition against Yehoshua. It is even stranger why the Torah would have commanded, in the first place, that the ceremonies take place specifically at Shechem (Devarim 11:29, 27:1-25).
Everything is solved if we say that the people of Shechem had a preexisting relation with the Israelites. Then it would be both practical and religiously desirable to hold the ceremonies there, even while the conquest was going on in the south. How could there be a preexisting relation? It makes perfect sense if you say the people of Shechem were descended from Avraham's followers.
In Yehoshua 24, Yehoshua gathers the people to Shechem and makes a covenant to observe the Torah. There are a number of difficulties with the passage. Why is new covenant needed at all, and why in Shechem? Shouldn't the covenants from Sinai and Moav be sufficient? Furthermore, Yehoshua delivers a detailed history of the Jewish people from Avraham until the last year of Moshe's life. Why must this whole story be told? Also, he offers the people the choice of idolatry versus Judaism. How can idolatry be an acceptable option for people who accepted the Torah at Sinai? And last, the idols he mentions are primarily not Canaanite or Egyptian, but Mesopotamian. What Jews or Canaanites would have been worshipping Mesopotamian idols?
Once again, the problems are solved by saying that we are talking about descendants of Avraham's followers. They came from Mesopotamia with Avraham, and never (fully) gave up their particular idolatry. Since they were never formally part of the Jewish people, they had the option of sticking with idolatry (perhaps, since they were not Canaanites, they could make that choice and avoid being massacred). The story of Jewish history would be news to people who did not leave Egypt themselves but were in Shechem at the time. And since they did not take part in any previous covenant, a new covenant was needed now, which had to be held in Shechem because that is where the people of Shechem lived.
(There is still some difficulty, because all of Israel was present and those making the covenant are simply referred to as "the people". But the only way to solve the above problems is by saying that "the people" refers to a specific group of outsiders, not to the nation as a whole. Yehoshua would have been deliberately mixing references to Israel and to the outsiders, to indicate that from now on they were to be considered one people.)
The population of Shechem is never again mentioned as being non-Jewish. According to Shoftim 8:33, 9:4, 9:46, though, the people of Shechem later on worshipped an idol called "Baal-Berit" or "El-Berit". Apparently this was some perversion of the original covenant made with Yehoshua, by which specifically Shechem agreed to accept Judaism.
In Shoftim chapter 9, Avimelech (son of the heroic Gideon, who came from outside Shechem) asked the people of Shechem to declare him king. His brother Yotam, whom Avimelech had tried to kill, went to Shechem and tried to dissuade them from making Avimelech king. Yotam told an allegory in which the trees decide to appoint a king among themselves. But the tall and fruitful trees - olive, fig, grape, cedar - all refuse to become king. Only the small and malicious thorn-bush agrees to become king over the greater trees. The obvious implication is that Avimelech was unsuited to rule. But the story may also shed light on the origins of Shechem's population. By saying that the smallest and most impermanent tree wanted to rule over the more well-rooted trees, Yotam may be hinting that the people of Shechem are part of an older and more established population than that from which Avimelech came. Specifically, Avimelech's family entered the land with Yehoshua, while the people of Shechem had a much longer history in the land, going back all the way to Avraham.
The same feeling of superiority might have caused Efraim and Menashe to resent the rule of Beit David, and played a part in their decision to rebel against Rehavam. (Idea suggested by D.F.)
3) EFRAIM AND MENASHE
According to Divrei Hayamim I 7:20-24, Efraim's descendants settled in Israel, within Efraim's lifetime. This is perplexing because by the time Yehoshua conquered the land, Efraim would have been several hundred years old, and probably dead.
It seems these people moved from Egypt to Canaan very early on, long before the rest of the people left Egypt. They remained there until Yehoshua came along and conquered the Canaanites surrounding them. Presumably they, like the descendants of Avraham's followers, accepted Judaism at the covenant in Shechem.
YAIR AND MACHIR
According to Bamidbar 32:39-41, Yair and Machir, two sons of Menashe, conquered land on the eastern bank of the Jordan. The same difficulty appears as before: shouldn't these sons have been very old or dead by the time of Moshe and Yehoshua? You could try the solve the problem by saying that their descendants, not them, did the conquering. But this is difficult to argue in light of Bamidbar 32:41, Devarim 3:14, and Yehoshua 17:1.
Once again, we solve the problem by saying that Yair and Machir conquered their land hundreds of years beforehand, and their conquests were ratified by Moshe when the Jewish people came along.
(Shoftim 10:3-4 is best understood as saying that one of Yair's descendants was also named Yair, perhaps in memory of his illustrious ancestor.)
Archaeologists tell us that at various times before Yetziat Mitzraim, the land of Canaan was either conquered by Egypt or part of an Egyptian sphere of influence. (Thus “Yosef gathered all the money that was found in the land of Egypt, and in the land of Canaan” [Breishit 47:14] – Canaan is mentioned alongside Egypt because they alone were part of the same empire.) This provides the conquest in which Yosef's grandsons would have done their conquering. Yosef was “prime minister” and they were likely still part of the Egyptian ruling establishment, so their conquests were coordinated with and part of the overall Egyptian quest for empire. Within the empire, Yosef's descendants likely traveled back and forth between Egypt and Canaan, with some ending up in each location when oppression began in later generations.
BRIT BEIN HABETARIM
In Brit Bein Habetarim, God explains to Avraham the trajectory of future Jewish history: "Know surely that your offspring will be a stranger in a land that is not theirs, and will serve them; and they will afflict them four hundred years; and also that nation, whom they will serve, I will judge; and afterward they will come out with great wealth. But you will go to your fathers in peace; you will be buried in a good old age. And the fourth generation will return here, for the sin of the Emorite is not yet full." (Breishit 15:13-16)
It seems that the beginning of this prediction contradicts the end: 400 years is longer than any reasonable interpretation of 4 generations. We see the periods of ~400 years and 4 generations cited elsewhere (Shemot 12:40; the ancestry of Moshe and other leaders of the Exodus generation), but both sides of the contradiction already appear – in greater clarity – in this single paragraph.
The most cited reconciliation is that the years and generations are measured from different starting points: Brit Bein Habetarim itself, versus the descent to Egypt or beginning of oppression.
But our Efraim/Menashe theory allows for a different answer. Perhaps some Israelites returned in the 4th generation, and the rest after 400 years. Efraim and Menashe were the fourth generation from Avraham, and by then the Emorites (who lived mainly on the east bank of the Jordan, for example Sihon and his kingdom) had sinned enough to deserve conquest. The remainder of the Jewish people in fact stayed a full 400 years in Egypt.
UNTIL THIS DAY
The phrase "ad hayom hazeh" - "...until this day" appears frequently in the Bible. However, since it indicates that the events in discussion happened a long time in the past, we would not expect to find it often in the Torah, which was transmitted to the Jewish people only shortly after most of the events it describes.
In fact, the phrase appears 12 times in the Torah. (In contrast, it appears 17 times in Sefer Yehoshua, which is roughly 8 times shorter than the Torah.) Of those 12 times, 10 of them refer to events which took place long before Moshe's time, or else are quotations from people's speech and are understandable in that context. The other two are difficult and theologically problematic.
One is Devarim 34:6, which describes Moshe's burial, saying that "no person knows his burial place until this day." Already in the gemara (Makkot 11a), one opinion states that these last few verses of the Torah were written by a prophet later than Moshe. (According to the other opinion, the verses are prophetic.) Either way, the problem is dealt with in Jewish tradition without affecting the integrity of the rest of the Torah.
The other is Devarim 3:14. "Yair son of Menashe took all the region of Argov, unto the border of the Geshurites and the Maacathites, and called them, even Bashan, after his own name, Chavot-Yair, until this day." The Jewish people under Moshe's leadership reached Bashan only a few months before Moshe's death. It's hard to believe that those few months were enough to justify the phrase "until this day". It probably takes more than a few months to conquer, repair the damage from war, move into new houses, and settle down, much less achieve the sense of permanence and history implied by the phrase "until this day".
But once you say that Yair conquered his lands decades or centuries earlier, and Moshe met up with his descendants, the problem disappears. The verse makes perfect sense, and one of the more difficult textual problems in the Torah is neutralized.
Sefer Bamidbar includes two censuses, one taken at the beginning of the 40-year period in the desert (chapter 1), and one taken 40 years later (chapter 26). Remarkably, the sizes of all the tribes are almost identical in the two censuses, with two exceptions.
One exception in Shimon, whose population declined drastically from 59300 (1:23) to 22200 (26:14). This can mostly be attributed to the sin with Baal Peor (25:1-8), after which 24000 people (presumably those who sinned) died in a plague. It seems that most or all of the 24000 were from the tribe of Shimon, which would go a long way towards explaining the decrease. There is much circumstantial evidence for this. The leading offender in the episode (25:14) was Zimri, a prince from Shimon. Devarim 29:17 suggests that it is likely that one tribe and only that tribe would turn to idolatry; quite likely this verse has in mind the episode of Baal Peor which happened only shortly beforehand. Furthermore, the tribes of Shimon, Gad, and Reuven traveled together in the desert. Gad and Reuven ended up together on the east bank, while Shimon lost its inheritance entirely. Apparently Shimon too originally would have received land on the east bank, in the Baal Peor area, but after the sin they were disinherited.
The other exception is Menashe, who increased from 32200 (1:35) to 52700 (26:34). Presumably this is not natural growth, since none of the other tribes had significant natural growth (or decrease). It makes more sense to say that part of the tribe of Menashe, which had been living on the east bank for decades or centuries, was now absorbed into the rest of the Jewish people.
In Bamidbar 32, the tribes of Reuven and Gad realize that the east bank of the Jordan would be a good place to live. They ask Moshe for permission, and Moshe agrees, after making them swear that they will help conquer the west bank with the other tribes. In the end, they as well as half the tribe of Menashe inherit land on the east bank. It is very curious, though, that the half of Menashe did not request their land from Moshe.
The problem is solved by saying that half of Menashe had already been living on the east bank and was now simply absorbed into the Jewish people. They did not ask for land because they already had it.
Yehoshua 1:12 indicates that half of Menashe did in fact commit to fight on the west bank in return for their land (this commitment is not mentioned in Bamidbar 32). It would not have been fair for Menashe to inherit land without sharing the burden of conquest, so the legitimacy of their inheritance was dependent on their participation in battle. If they chose to avoid the fighting, then their title to the land would be retroactively annulled.
ARVOT MOAV COVENANT
Devarim 28 (and arguably Devarim 30 too) consists of a new covenant between God and the Jewish people - "These are the words of the covenant which God commanded Moses to make with the children of Israel in the land of Moav, beside the covenant which He made with them in Horev." (28:69). We can ask the same question as with the Shechem covenant: after Mount Sinai, why was a new covenant needed?
Once again, we solve the problem by saying that the covenant was for the benefit of those who had not been at Sinai. This was the explanation we gave for the Shechem covenant, and it works here too, regarding the half-tribe of Menashe which had not been at Sinai.
Perhaps Devarim 29:13-14 ("I do not make this covenant and oath with you alone, but rather with those who stand here today before Hashem our God, as well as those who are not here with us today") refers to members of Efraim or Menashe who were not present with the main Jewish people at this ceremony.
It may be that the covenant in Sefer Nechemiah (9:1-10:40) was also about the addition of new people. Verse 9:2 indicates that all intermarriages were broken up, but 13:1 implies that some Ammonites and Moavites were still married to Jews. The verses are reconciled by saying that in chapter 9, mixed marriages could be saved if the foreign spouse converted to Judaism. But later on it was discovered that Ammonites and Moavites could not marry Jews even after conversion, so some converted couples were forced to separate. Thus, in chapter 9 it seems than many spouses did convert to Judaism, and this mass conversion was what precipitated the making of a covenant.
You could argue that sometimes national covenants are made without any formal reason, but just to commemorate large-scale repentance. This position is problematic; halachically you can't make an oath on something your ancestors swore to do at Sinai. In three cases - Arvot Moav, Shechem, and Nechemiah - we can nicely avoid this problem by saying that new people were involved. I don't want to definitively say that EVERY covenant in Tanach must involve new people, but it seems like an effective explanation which should be applied whenever possible.
DESCENT FROM AVRAHAM
According to the famous midrash in Pesikta Rabbati 21:3, before giving the Torah to Israel, God offered it to various other nations. Esav rejected the Torah because it outlawed murder and one of Esav's national characteristics was bloodshed. Similarly, Ammon rejected the Torah because Ammon was descended from an incestuous relationship, and Yishmael rejected the Torah because Yishmael's livelihood depended on theft. Finally, God went to Israel, and Israel agreed to accept the Torah.
One wonders why God would offer the Torah to people who were not part of God's promise to Yaakov and who had not been redeemed from Egypt by signs and wonders. But the nations in the midrash have one striking commonality: all of them are descended from Avraham (or his nephew Lot). It appears that since the original promise had been to Avraham, thus any of Avraham's descendants could have accepted the Torah. Meanwhile, the Canaanites, Phoenicians, and Egyptians - nations located nearby at the same time, but not related to Avraham - did not have the same option.
The sufficiency of descent from Avraham is very interesting in relation to the thesis of this post. We have suggested that thousands of Avraham's followers, as well as parts of the tribes of Efraim and Menashe, were in much the same position as Esav, Ammon, and Yishmael. Outside the normative Jewish people, but descended from or loyal to Avraham, it seems that these groups were offered the Torah on an optional basis. But unlike Esav, Ammon, or Yishmael, our groups accepted the Torah and from then on became part of the Jewish people.
(An apparent difficulty is that blessings offered by the Avot do not picture Esav or Yishmael as continuing God's special covenant with them. But presumably the blessings are only a bottom line, and through proper behavior Esav or Yishmael could aspire to reach a stronger relationship with God. In any case, the blessings Shimon and Levi received were not too promising either, and they managed to remain Jewish.)
Thus, unexpectedly, we are led to read the midrash almost literally. Presumably there was no formal event in which Esav, Ammon, and Yishmael learned about Judaism and decided to reject it. But, to use a metaphor from Breishit 19, God probably sent a pair of angels to bear witness that they were unfit to receive the Torah. If the angels had found otherwise, then we might have had even more covenant ceremonies, and ended up with a significantly larger Jewish people.
There are significant implications regarding the idea of "outcast" or "nidcheh" which is used to explain the progression of Sefer Breishit. It seems the status of "outcast" was not at all as absolute as one might assumed. Rather than meaning permanent expulsion, being "outcast" is more of a temporary status, of being overlooked for a limited time while the Divine plan focuses on another individual. When Yosef, according to R' Yoel Bin Nun's explanation, continued living an exemplary moral life even after he thought he had been expelled from Yaakov's family, perhaps he was not only displaying personal integrity. Perhaps he knew that at some point he or his descendants would be able to rejoin the Jewish people, and he was anticipating and preparing for that day.
Why, if it's so clear that early inheritance of the land happened as I describe, would it not be explicitly mentioned anywhere in Tanach? (Perhaps Divrei Hayamim's discussion of Efraim counts as explicit, but at least there is no clear reference in the Torah, which is when the events would have happened.) Here are two possible explanations for this “cover-up”.
1) If all the various presentations of the Torah except for Sinai are covered up, then it emerges that everyone who was presented the Torah was required to accept it. By seeing the original giving of the Torah as unavoidable and inescapable, we may be led to see our Torah observance the same way. Avoiding the mention of an "optional" Torah may increase our own sense of duty and responsibility.
This explanation may not speak to us in the modern era, when our lives are usually secure due to human efforts, and religion typically seems more like a worthwhile choice than an unavoidable obligation. In the ancient world, though, I suspect this explanation would have sounded a lot stronger.
2) Another possible reason is to maintain unity within the Jewish people. The people of Shechem would be tempted to look down at the rest of the nation as upstarts and ex-slaves, less honorable and with less connection to the Land of Israel than themselves. In turn, they would be attacked for not having "really" accepted the Torah from God, which is to say in a miraculous event at Sinai, and because they were not even genetically descended from Avraham. Given the extreme factionalism which was present throughout much of the Biblical period, it is clear that Tanach would not want to immortalize further internal distinctions by unnecessarily recording them in the text.
UPDATE: some more discussion of this topic can be found in section 1.2 here.