Because Coriantum is righteous, the promise of the land is effectual for him. He builds “many mighty cities,” meaning, in a Mesoamerican context, that he allowed important relatives, or other important lineages, to establish new cities. Though immediately under the control of their founder, the new cities would maintain their allegiance to Coriantum’s capital.
Coriantum’s first wife is childless, but his second wife had children. As an incident of this information, Moroni mentions that Coriantum lived to age 142, if we can accept that as accurate rather than somehow symbolic. That number is two years short of the very significant and possibly artificial 144 (12x12).
Chronology: Coriantum’s long life suggests greater elasticity in determining average lifespans, and therefore the average reign-length. However, even that flexibility does not cover the missing two thousand years between the Jaredite beginning dates espoused by Sorenson and Palmer and the one that I reconstruct. Using the average reign would date Coriantum’s from 920 to 890 B.C., although his is obviously longer than average.