Mormon ends the book of Mosiah with the passing of the two most important men discussed in the book, King Mosiah and Alma the elder. In terms of ancient lifespans, both men were aged, but Alma the elder was impressively older, passing away at eighty-two years of age.
As noted at the beginning of our book of Mosiah, we do not have the original beginning of the book. It certainly began with the establishment of the change from a solely Nephite king to a king over both Nephites and Zarahemlaites. It ended with another political change with the beginning of the reign of the judges. Although a modern reader sees both religion and politics in the chapter, they were anciently so closely related as to be difficult to separate. Thus, while there were religious ramifications, the book of Mosiah has been a story of political change.