The Church of the East began evangelizing Gilan in the 780s, when a metropolitan bishopric was established under Shubhalishoʿ. In the 9th and 10th centuries AD, Deylamites and later Gilanis gradually converted to Zaidite Shi'ism. Several Deylamite commanders and soldiers of fortune who were active in the military theaters of Iran and Mesopotamia were openly Zoroastrian (for example, Asfar Shiruyeh a warlord in central Iran, and Makan, son of Kaki, the warlord of Rey) or were suspected of harboring pro-Zoroastrian (for example Mardavij) sentiments. Muslim chronicles of Varangian (Rus', pre-Russian Norsemen) invasions of the littoral Caspian region in the 9th century record Deylamites as non-Muslim. These chronicles also show that the Deylamites were the only warriors in the Caspian region who could fight the fearsome Varangian vikings as equals. Deylamite mercenaries served as far away as Egypt, Islamic Spain, and in the Khazar Kingdom.