The Crimea was Greek-speaking for more than a thousand years as a part of the Byzantine Empire. After the Fourth Crusade's sacking of Constantinople fragmented the Byzantine Empire, the Crimea became a principality within the Greek Empire of Trebizond. When that state, which was centered on the eastern Black Sea coast and Pontic Alps of northeastern Anatolia, fell to the Ottomans in 1461, the Crimean Greek principality (Principality of Theodoro) remained independent, becoming subject to the Ottomans in 1475. Crimean Greeks became divided into two sub-groups: Tatar-speaking Urums and Romaiic Pontic Greeks with Rumeíka Greek as their mother tongue.