[1] Oshin became king after the murder of his nephew Leo III and brother Hethum II at a feast at the hands of the Mongol general Bilarghu.

Like his brother Hethum II, Oshin favored a union of the Armenian and Roman churches, which aroused no little popular discontent.

The unification of these churches was a precondition to obtain help from Europe, but also a matter of huge popular discontent as the Catholic Crusader states had previously been involved in a number of deadly border clashes with the Armenian Kingdom of Cilicia.

Nevertheless, Oshin appealed to Christian Europe as by his reign, the kingdom of Armenian Cilicia to protect his regions against the Muslim Mamluk Empire and the Ilkhanate .

The Mongols were no longer a reliable ally as they were themselves weakened by this point due to constant wars with the Mamluks and infighting within the state.