Gardner observes that based on Ether 7:1–2, Orihah the Jaredite king was probably a polygamist.
Brant A. Gardner, Second Witness: Analytical and Contextual Commentary on the Book of Mormon, six vols. (Salt Lake City: Kofford Books, 2007), 6:236
Thirty-one children strongly suggests that Orihah had more than one wife. Polygamy was common early in the biblical record (even Jacob references David and Solomon, Jacob 1:15), so it should not surprise us that it would be practiced by men coming from that time and place. In the New World, polygamy was an adaptive strategy that helped transform smaller social units into larger and more successful ones. (See commentary accompanying Jacob 2:32–24.)