Nicephorus Gregoras
Nicephorus Gregoras is unique in claiming that Kaykaus first made contact with the Bulgarian tsar, Konstantin Tikh, who enlisted his Mongol overlords. He admits, however, that the Mongol element was predominant in the invading army. He says that they came from Paristrion, that is, just north of the lower Danube. He gives their number as two thousand (or two tumens). According to Pachymeres, they were an autonomous band, "de facto" independent of the authority of the Golden Horde. If he is correct, then they were probably not under the leadership of Nogai Khan and were acting as mercenaries (to be paid in booty) of the Bulgars.