The Koreanic languages are likely not native to Jeju Island; it has been proposed that the family has its roots in Manchuria, a historical region in northeastern Asia. It is thought that Koreanic speakers migrated from southern Manchuria between the third and eighth centuries CE. Linguist Alexander Vovin suggests that the ancient kingdom of Tamna, which ruled the island until the twelfth century, may have spoken a Japonic language that left a substrate influence on Jeju. When exactly this putative Japonic language may have been replaced by the Koreanic ancestor of Jeju remains unclear.