Mongol invasion of Thrace
The Mongol invasion of Thrace took place in the winter of 1264/1265, under the leadership of Nogai Khan.
Background
The Seljuk Sultan Kayqubad II appealed to Berke, khan of the Golden Horde to attack the Byzantine Empire in order to free his brother Kaykaus II.
Invasion
With the assistance of the Second Bulgarian Empire (then vassal of the Golden Horde), around 2 tumens under the leardership of Nogai Khan crossed the Danube river and invaded Byzantine Thrace. Nogai defeated the armies of the Byzantine emperor Michael VIII Palaiologos in the spring of 1265. While most of the defeated army fled, the Byzantine Emperor likewise escaped with the assistance of Italian merchants. After that Thrace was plundered by Nogai's army.
Aftermath
Michael VIII was forced to release Kaykaus, and signed a treaty with Berke, in which he agreed to give one of his daughters, Euphrosyne Palaiogina, in marriage to Nogai. Berke ceded Crimea to Kaykus as appanage and agreed that he would marry a Mongol woman. Michael also sent tribute to the Horde.