 Complete the following phrase:  During the Russian campaign in the 13th century, the Mongols drove some 40,000 Cuman families, a nomadic tribe, west of the Carpathian Mountains. The Iranian Jassic people came to Hungary together with the Cumans after they were defeated by the Mongols. Over the centuries they were fully assimilated into the Hungarian population. Rogerius of Apulia, an Italian monk who witnessed and survived the 