Biographical: The sparse evidence of the break between Abinadom's writings and Amaleki's suggests that Abinadom did not make the trek to Zarahemla, and died in Nephi. However, since Abinadom did not take care to give the plates to any other (such as a brother) we may also expect that he knew he had a son to whom they would be given, but that his son was too young to receive them at that time.
Amaleki tells us: "Omni 1:23 Behold, I, Amaleki, was born in the days of Mosiah…" Mosiah does not become a king until he is in Zarahemla, and we would not normally expect that "the days of" would apply to a time prior to his political rule. However, in retrospect, it may have been just as easy a way to indicate the general era of his birth. Because Abinadom does not reassign the plates elsewhere, I shall presume that Amaleki was very young, and traveled with his mother (but not his father) on the trip to Zarahemla.
Textual: After so many writers who have had nothing to say, Amaleki has very important information, but he condenses it tremendously. We do get the summary of events, not the written history while they occur. Amaleki is clearly writing well after these events have taken place. If we go with the hypothesis that Amaleki was very young when the exodus occurs, that fact would explain why his account is retrospective rather than first hand, he might have been too young to have all of the important details.
While the shorter length of the earlier entries virtually guaranteed that they were written in a single sitting, Amaleki's record also appears to be written in a single sitting near the end of his life. As he sees his end near, he decides to write the important historical events he has witnessed. Having written of them, he closes the record. There are no breaks in style nor narrative that would suggest that he left the material and returned to it.
Stylistically, it also appears to be the writing of one who is composing as he is writing, rather than carefully composing and then writing. He doesn't tell us of how he is witness to the events until they have been recorded, and the ending of the book in particular has the feel of someone who is wandering through his own narrative rather than closing powerfully (such as Nephi did, for instance).
History: One of the most significant events in the history of the Nephites occurs in verse 12, and passes in the second half of the sentence. With so little to go on, once again we are left to reasoned speculation to fill in the gaps of the events.
The first known fact is that Mosiah receives a commandment from the Lord to flee the land of Nephi. This fact virtually assures us that Mosiah is a prophet (prophets are clearly not lineage based in the Book of Mormon). The second interesting fact about Mosiah is that he is made king over Zarahemla.
What Amaleki does not tell us is Mosiah's status in Nephi. Since he was made king in Zarahemla, we might want to assume that he was also king in Nephi, but that would be an unsupported assumption. In fact, strong inference may be made that Mosiah was not the king.
Jacob told us that the kings of Nephi took upon themselves the name Nephi:
" Jacob 1:11 Wherefore, the people were desirous to retain in remembrance his name. And whoso should reign in his stead were called by the people, second Nephi, third Nephi, and so forth, according to the reigns of the kings; and thus they were called by the people, let them be of whatever name they would."
Using the model of other historical kings, the acceptance of rule initiated a formal change in name, a change that signified a transformation from the "common" into the "regnal." We should assume, therefore, that once a king in Nephi, the person would be called Nephi, and not return to a previous name. Not only do we have Mosiah named as Mosiah (and not Nephi the X) but the tradition of naming the ruler of the people of Nephi after Nephi completely disappears from the Book of Mormon from this point on. While we have no confirming evidence of the continuation of the practice from Jacob to Amaleki, it is very clear that after the time of Mosiah it is not a tradition at all. Why not?
The easiest explanation is that Mosiah was a prophet, but not the king. When the command to flee came, it came as it did to Nephi when his brothers threatened. The group of people who leave have nearly the same categorical designation as did those who followed Nephi. Those who follow Mosiah are: "…as many as would hearken unto the voice of the Lord…"
Mosiah leaves with only a portion of the population of Nephi. What might we make of this? If we piece together the continuing puzzle of Nephite political life, we have a city continually under siege from various Lamanite populations. The increasing pressure from the Lamanites suggests two plausible scenarios for the command to flee:
One: The city was under threat of another attack that the Lord knew would be more effective than previous attacks. Thus Mosiah and the righteous were asked to flee the destruction.
Two: The pressure from the Lamanites was ameliorated by accommodation to the Lamanite culture. This would have been an official capitulation by the rulers, and the city would have continued, but the environment would have been untenable for the righteous.
While the first is more straightforward, the second serves as a better explanation of why the king is not the one leading the exodus. Were the king of the Lamanites to go with Mosiah, we should have known it, and the right of kingship would have been to that Nephi upon entering Zarahemla. Assuming the analysis of the names of the kings is correct, the absence of the king must be explained. The king is either dead, or chooses to remain. It was rare to have a king endangered, and so we can reasonably assume that the king chose not to go.
When we return to the undercurrent of acculturation that flows through Nephite history and the tension between the religious and the wealthy, a break between the religious (those who head God's call through Mosiah) and the worldly/wealthy (who follow the king) is quite understandable, with the tension finally erupting into division. Unlike the event that precipitated the break between Nephi and his brothers (the death of Lehi) we don't have a single event to which we can ascribe this particular division, but the noted increase in warfare suggests that it is the Lamanite pressure that causes it - a pressure that is resolved in either victory, defeat, or accommodation. The way I read the evidence, I suggest that it was accommodation.
Archaeological: When Mosiah flees the city, we may rightfully ask why he chose to go in the direction he did. Of course the Lord was leading him, but it was also a natural direction for him. As Sorenson notes, there is no southward travel out of Nephi mentioned (Sorenson p. 12).
What there is to the more northerly direction (through the wilderness area) is a known trade route. Trade routes are difficult to trace archaeologically, but they may be presumed when an identifiable trade good moves from one location to another. In the case of Kaminaljuyu (Sorenson's identification for Nephi) a major export was obsidian. The source for the obsidian was close by, and the obsidian was even worked in Kaminaljuyu.
The creation of obsidian leaves sufficient traces of its location that pieces of obsidian found long distances away can be accurately traced to their source. The Kaminaljuyu obsidian is known as El Chayal. The trade in El Chayal obsidian in the early years of the Book of Mormon would have been down through the coast, but at the time period we are examining, it appears that a primary distribution channel had been developed whereby El Chayal obsidian is traded into Veracruz, which is Northwest of Kaminaljuyu. (Pires-Ferreira, Jane W. "Obsidian Exchange in Formative Mesoamerica." In: The Early American Village. New York, Academic Press. 1976, p. 302-3).
Thus there were already cultural predispositions to move north, and the sure knowledge that there were friendly towns in that direction. Mosiah's flight northward is therefore fully understandable.