letter of thanks he received from Pope John XXII in which the Christian leader thanked Öz Beg for his kind treatment of Christians. Öz Beg had sent a letter to the Metropolitan Peter which stated:By the will and power, the greatness and most high! Let no man insult the metropolitan church of which Peter is head, or his service or his churchman; let no man seize their property, goods or people, let no man meddle in the affairs of the church...Their laws, their churches and monasteries and chapels shall be respected; whoever condemns or blames this religion, shall not be allowed to excuse himself under any pretext, but shall be punished with death. Reign Military and politics Öz Beg maintained one of the largest armies in the world, which exceeded 300,000 warriors. He employed his military clout to conduct campaigns against the Ilkhanate in Azerbaijan in 1319, 1325 and 1335. Ilkhanid commander Chupan repulsed one Öz Beg's first two attempts and even invaded deep into the Jochid Ulus in 1325. Öz Beg found an ally against the Ilkhanids in Mamluk Egypt; indeed, one of Cairo's squares was named after him. The Khan had the daughter of previous Khan's sister, Princess Tulunbuya, married to a Mamluk sultan, but she died in a few years. The khan instructed his merchants to lend 27,000 dinars to the Mamluk ambassador in order to finance the feast for the bride at Sarai. Soon after Öz Beg was disappointed with the Mamluk sultan's divorce with Tulunbuya and indecisiveness regarding the joint invasion of Ilkhanate. In 1323, a peace treaty was signed between Egypt and the Ilkhanate. This situation nullified the alliance and the Mamluks refused to invade the Ilkhanate. Öz Beg's next incursion coincided with Abu Said's death. However, the weather turned bad and the new Ilkhan Arpa Ke'un came with a large force; Öz Beg's army was forced to withdraw. Prior to and during the Esen Buqa–Ayurbarwada war, Chagatai Khan Esen Buqa I attempted to gain the support of Öz Beg Khan against Ayurbarwada Buyantu Khan, the Great Khan of the Mongol Empire and the Emperor of the Yuan dynasty, in 1313 and 1316. Esen Buqa warned Öz Beg that the Great Khan would overthrow him from the throne of the Horde and install another Khan from the Jochids instead. But Öz Beg's vizier convinced him not to believe this and the Khan refused to