The multiethnic "Gutthiuda" was divided into smaller political units or "kuni", each headed by tribal chiefs or "reiks". In case of emergency, the tribal chiefs' council elected a supreme leader who was known as "iudex regum" ("judge of kings") by St Ambrose. Christian prisoners of war were the first missionaries among the Goths. Ulfilas, himself a descendant of a Cappadocian captive, was ordained bishop "of the Christians in the land of the Goths" in 341. Expelled from "Gutthiuda" during a persecution of Christians, Ulfilas settled in Moesia in 348.