Öz Beg, whose total army exceeded 300,000, repeatedly raided Thrace in aid of Bulgaria's war against Byzantium and Serbia beginning in 1319. The Byzantine Empire under Andronikos II Palaiologos and Andronikos III Palaiologos was raided by the Golden Horde between 1320 and 1341, until the Byzantine port of Vicina Macaria was occupied. Friendly relations were established with the Byzantine Empire for a brief period after Öz Beg married Andronikos III Palaiologos's illegitimate daughter, who came to be known as Bayalun. In 1333, she was given permission to visit her father in Constantinople and never returned, apparently fearing her forced conversion to Islam. Öz Beg's armies pillaged Thrace for forty days in 1324 and for 15 days in 1337, taking 300,000 captives. In 1330, Öz Beg sent 15,000 troops to Serbia in 1330 but was defeated. Backed by Öz Beg, Basarab I of Wallachia declared an independent state from the Hungarian crown in 1330.