The Lamanite King reigned during the final Nephite-Lamanite wars that ended at Cumorah around AD 385. In the year marking 360 years since the coming of Christ, he sent an epistle to the Nephite leader Mormon informing him that the Lamanites were again preparing to come to battle (Mormon 3:4).
Mormon later wrote an epistle in return, asking the king to grant that the Nephites might gather their people to the land of Cumorah, by a hill called Cumorah, to give battle there (Mormon 6:2). The king granted the request (Mormon 6:3).
The record gives no name or other personal detail for this king.