This paper examines the foreign policy of the Galician-Volhynian prince Roman Mstislavich. Roman became the main military ally of the Byzantine Empire in the early 13th century. Byzantium was going through a severe political crisis caused by the Serbian and the Bulgarian uprisings and by the crushing raids of the Cumans. According to Niketas Choniates, the nomads' aggression could have been stopped only thanks to the aid of the Galician prince Roman. The circumstances and the time of Roman's campaign in Choniates' account are the same as in the Russian chronicles reporting the steppe campaigns of the Galician-Volhynian prince.