We have very little information about the development of the Lamanite society after Nephi led his group of followers from the original settlement in the land south (Lehi) to NEPHI. Whatever the reason, prior to Mosiah 24, the Lamanites were not a cohesive society, as were the Nephites.
However, during the days of Alma and Limhi, a radical change took place through the influence of Amulon, one of Noah's priests. Amulon "did gain favor in the eyes of the king of the Lamanites," and King Laman appointed Amulonites to be teachers "in every land which was possessed by his people" (Mosiah 24:4). The Amulonites taught the Lamanites to keep records, to correspond with each other, and to establish trade (Mosiah 24:6-7). In result, Lamanite wealth and "wisdom of the world" increased dramatically (Mosiah 24:7). Each Lamanite land had its own king, but these kings were both appointed and governed by the King over all the Lamanites (Alma 20:26).
With all the emphasis on the Lamanites in NEPHI, we lose sight of the Lamanites still living in Lehi, south of the Isthmus of Darien. Mormon reminds us of them in Helaman 6:9-12, when he speaks of the wealth of both Nephites and Lamanites living in both the land north and the land south.
If we had no winter, the spring would not be so pleasant; if we did not sometimes taste of adversity, prosperity would not be so welcome. Anne Bradstreet
And if men come unto me I will show unto them their weakness. I give unto men weakness that they may be humble; and my grace is sufficient for all men that humble themselves before me; for if they humble themselves before me, and have faith in me, then will I make weak things become strong unto them. Ether 12:27
Yea, all things which come of the earth, in the season therof, are made for the benefit and the use of man, both to please the eye and to gladden the heart; Yea, for food and for raiment, for taste and for smell, to strengthen the body and to enliven the soul. And it pleaseth God that he hath given all these things unto man; for unto this end were they made to be used, with judgment, not to excess, neither by extortion. D&C 59:18-20