This empire lasted for more than 250 years until it eventually fell at the hands of Mehmed II of the Ottoman Empire in 1461. However it took the Ottomans 18 more years to finally defeat the Greek resistance in Pontus. During this long period of resistance many Pontic Greeks nobles and aristocrats married foreign emperors and dynasties, most notably of Medieval Russia, Medieval Georgia, or the Safavid Persian dynasty, and to a lesser extent the Kara Koyunlu rulers, in order to gain their protection and aid against the Ottoman threat. Many of the landowning and lower-class families of Pontus "turned-Turk", adopting the Turkish language and Turkish Islam but often remaining crypto-Christian before reverting to their Greek Orthodoxy in the early 19th century.