The region was a province, Garmekan, under the Sasanians. It was a prosperous metropolitan province centered at Karkha D'Beth Slokh (Kirkuk), It had a substantial Assyrian population who mostly followed the Church of the East until the fourteenth century, when the region was conquered by Timurlane, who conducted massacres of the indigenous Assyrian population of what is today Northern Iraq, Southeast Turkey and Northeast Syria.[4]