Cumans
The Cumans or Kumans were a nomadic East Turkic tribe living on the north of the Black Sea along the Volga. They are identified with the Western branch of the Kipchaks.
They invaded Moldova, Wallachia and part of Transylvania in the 11th century and from here they continued their plundering of the Byzantines, Hungarians and Kievans. In 1089, they were defeated by Ladislaus of Hungary, then they were again defeated by the Slavs in the 12th century and crushed by the Tatars in the 1241. Many took refuge in Hungary and Bulgaria, where they were assimilated. The Cumans from the current Russia joined the khanate of the Golden Horde.
In the 13th century, the Cumans became Catholic Christians, a "Diocese of the Cumans" being created, that included Romania and Bessarabia, this title being kept until 1523.