The Russo-Turkish War (1768–74) resulted in the defeat of the Ottomans by the Russians, and according to the Treaty of Küçük Kaynarca (1774) signed after the war, Crimea became independent and the Ottomans renounced their political right to protect the Crimean Khanate. After a period of political unrest in Crimea, Russia violated the treaty and annexed the Crimean Khanate in 1783. After the annexation, the wealthier Tatars, who had exported wheat, meat, fish and wine to other parts of the Black Sea, began to be expelled and to move to the Ottoman Empire. Due to the oppression by the Russian administration and colonial politics of Russian Empire, the Crimean Tatars were forced to immigrate to the Ottoman Empire. Further expulsions followed in 1812 for fear of the reliability of the Tatars in the face of Napoleon's advance. Particularly, the Crimean War of 1853–1856, the laws of 1860–63, the Tsarist policy and the Russo-Turkish War (1877–78) caused an exodus of the Tatars; 12,000 boarded Allied ships in Sevastopol to escape the destruction of shelling, and were branded traitors by the Russian government. Of total Tatar population 300,000 of the Taurida Governorate about 200,000 Crimean Tatars emigrated. Many Crimean Tatars perished in the process of emigration, including those who drowned while crossing the Black Sea. In total, from 1783 till the beginning of the 20th century, at least 800 thousand Tatars left Crimea. Today the descendants of these Crimeans form the Crimean Tatar diaspora in Bulgaria, Romania and Turkey.