After the Mulekites arrived, they "had many wars and serious contentions, and had fallen by the sword from time to time" (Omni 1:17). If the Mulekites arrived a short time after Lehi, and they were discovered by Mosiah1 in about the year 397, that is a difference of roughly 380 years. If the land of Zarahemla was a little more than 21 days away from the land of Nephi according to the travels of Alma1, or 40 days away from the local land of Nephi according to the travels of Ammon, how come we don't hear about those Mulekite wars affecting life among the Nephites or Lamanites in the Nephite records? One possibility might come in the sparsity of the historical record itself. In view of the fact that even the Nephite history of 400 years is covered in only a few pages, the non-mention of the people of Zarahemla might not be so hard to understand.
John Sorenson notes that one might wonder why the Nephite historians didn't mention "other" people more explicitly in their record? . . . This lack of concern has to do with the fact that the focus of the Nephite record is the Nephites. [John Sorenson, "When Lehi's Party Arrived, Did They Find Others in the Land?", F.A.R.M.S., p. 24] [See the commentary on Omni 1:15]
As far as the "wars and serious contentions" mentioned by Amaleki, they might have had something to do with the Jaredite people. According to John Sorenson, in the course of amalgamation, the newcomers probably adopted the local tongue . . . The subsequent wars among the immigrants reported in Omni 1:17 could well have been complicated by historical quarrels among the local [Jaredites] with whom they had become involved.
Nothing is said about how much time passed before the people of Zarahemla left their landing place to move "up into the south wilderness" (Alma 22:31), perhaps along the Sidon river, for they settled beside it. . . . Nowhere do we get a hint that the descendants of the people of the ship(s) that brought Mulek constituted a single political/ethnic unit prior to Zarahemla's day. No comprehensive term such as Mulekite is used to embrace them, suggesting that not all of those descended from those immigrants recognized Zedekiah's son as their head, nor perhaps any other one person. There may have been differences among the group over authority from the first, resulting ultimately in political fragmentation, with Zarahemla's group just one tribelet among a number tied chiefly by economic links. . . .
When the forefathers of Zarahemla's people reached the area that would become the land of Zarahemla, they likely had left others of their tradition behind in the lowlands where they originated. But at least by the time the stone of Coriantumr was fetched (Omni 1:20), these folks on the upper river must have had peaceful relations with those others. . . . [John L. Sorenson, "The Mulekites," F.A.R.M.S., pp. 12, 14-16]