The beginning of the reign of Mosiah is the beginning of the end of royal government among the Nephites. Mosiah explains that such a form of government is healthy if the king is righteous like his father:
'Therefore, if it were possible that you could have just men to be your kings, who would establish the laws of God, and judge this people according to his commandments, yea, if ye could have men for your kings who would do even as my father Benjamin did for this people--I say unto you, if this could always be the case then it would be expedient that ye should always have kings to rule over you. (Mosiah 29:13)
However, Mosiah acknowledges that because all men are not just it is not expedient that ye should have a king (Mosiah 29:16). Therefore, the practice ends. With the exception of a secret combination that referred to their leader as a king (3 Nephi 7), there are no more Nephite kings. Accordingly, Amulek refers to Mosiah as our last king (Alma 10:19)
In spite of the fact that Mosiah is the last Nephite king, we are about to read of three other kings, Zeniff, Noah, and Limhi. However, this record, as contained in Mosiah 9-22, is a flashback to a previous time and a different group of people.