During the reign of Berke there was also a raid against Thrace. In the winter of 1265, the Bulgarian czar, Constantine Tych, requested Mongol intervention against the Byzantines in the Balkans. Nogai Khan led a Mongol raid of 20,000 cavalry (two tumens) against the territories of Byzantine eastern Thrace. In early 1265, Michael VIII Palaeologus confronted the Mongols, but his smaller squadron apparently had very low morale and was quickly routed. Most of them were cut down as they fled. Michael was forced to retreat to Constantinople on a Genoese ship while Nogai's army plundered all of Thrace. Following this defeat, the Byzantine emperor made an alliance with the Golden Horde (which was massively beneficial for the latter), giving his daughter Euphrosyne in marriage to Nogai. Michael also sent much valuable fabric to Golden Horde as tribute.