Hungary adopted an expansionist policy after Boris's attempts to dethrone Béla. The chronicler Thomas the Archdeacon relates that Gaudius, who became Archbishop of Split in 1136, "enjoyed great favor with the kings of Hungary" and "often visited their court". The report suggests that Split accepted Béla II's suzerainty around 1136, but this interpretation of the sources is not universally accepted by historians. The exact circumstances surrounding the submission of Bosnia are unknown but the region seems to have accepted Béla's suzerainty without resistance by 1137. Historian John V. A. Fine writes that the northeastern regions of the province formed part of Queen Helena's dowry. The Hungarian army penetrated into the valley of the Rama River, a tributary of the Neretva River, in about 1137. Although Béla assumed the title King of Rama in token of the new conquest, the permanent occupation of the region is not proven.

Hungarian troops participated in a campaign launched by Grand Prince Yaropolk II of Kiev against Vsevolod of Kiev in 1139. Béla strengthened his alliance with the Holy Roman Empire. For this purpose, he gave financial support to Otto of Bamberg's missions among the Pomeranians and arranged the engagement of his daughter Sophia with Henry, son of the new German king Conrad III in June 1139.