This verse highlights Mormon’s authorial process. In verse 23, he summed up an ideal time. The Savior had come to them, and his influence engendered peace and prosperity for two hundred years. The precision of that number and the apparently sudden emergence of “costly apparel” and prideful people signals Mormon’s narrative control. Of course, a passion for costly apparel did not instantly sweep Nephite society in the 201st year after Christ. It had been coming for a long time. “Costly apparel” is Mormon’s code for influence from the surrounding cultures. (See commentary accompanying Jacob 2:12–13.) Hard on its heels come social hierarchies and the rest of the invasive cultural package that has plagued the Nephite culture from the beginning.
History: It seems impossible that Nephite society, after two centuries of stability, began to change only in the 201st year, then plummeted for the next seventy or eighty. For this reason, I argue that 4 Nephi represents Mormon’s construction, rather than a faithful record of events.
The first two hundred years correspond to a general mini-collapse. The eruption of Ilopango in San Salvador between 200 and 250 created a historical event that clearly divided time around A.D. 200 into a before and after, reflecting Mormon’s conceptual division. (See 4 Nephi, Part 1: Context, Chapter 1, “Historical Background of 4 Nephi through Mormon.”) I am not claiming that Mormon ignored history, just that he molded it.