fter the defeat of the Byzantines by the Turks at the battle of Bapheus in 1302, Turkish expansion in Asia Minor proceeded at a very rapid pace. The Byzantine defence in that region had already begun to weaken since the time of Michael VIII. Andronikos II, in order to confront the Turkish expansion, gladly accepted the offer made to him by Roger de Flor, the leader of the Catalan Grand Company, to fight together with his mercenaries against the Turks.

In 1304 the Catalans defeated the Turks, who were besieging Philadelphia, and liberated the city. But after their victory, on pretext that the Byzantine emperor had not paid them their wages, they embarked on a spree of plundering and looting, finally attacking the Byzantine city of Magnesia. After the assassination in 1305 of their leader, Roger, in the palace of Andronikos' son, Michael IX, they set themselves to wreaking still greater havoc. To revenge themselves on the Byzantines, they pillaged part of Thrace and Macedonia, not sparing the monasteries of Mount Athos. Afterwards, they invaded Thessaly and finally, having defeated the Franks of the Duchy of Athens at Kifissos, in Boeotia, in March 1311, they set up in Athens a state of their own, which survived until 1388.

The strange course of the Catalans, which led them from Asia Minor to Athens, undoubtedly shows how weak not only Byzantium, but also the other small states of the Greek mainland had become. Taking advantage of the Catalans' turn toward Frankish Greece, Andronikos II strengthened the Byzantine possessions in the Morea and appointed there as permanent governor, first Michael Kantakouzenos and then Andronikos Asen Palaiologos. At almost the same time he extended Byzantine rule over the region of the despotate of Epiros and of the state of Thessaly (1318).