The Don Cossacks and Kalmyk Mongols also managed to raid Crimean Tatars' land. The last recorded major Crimean raid, before those in the Russo-Turkish War (1768–74) took place during the reign of Peter the Great (1682–1725). However, Cossack raids continued after that time; Ottoman Grand Vizier complained to the Russian consul about raids to Crimea and Özi in 1761. In 1769 one last major Tatar raid, which took place during the Russo-Turkish War, saw the capture of 20,000 slaves. Nevertheless, some historians, including Russian historian Valery Vozgrin and Polish historian Oleksa Gayvoronsky have emphasized that the role of the slave trade in the economy of the Crimean Khanate is greatly exaggerated by modern historians, and the raiding-dependent economy is nothing but a historical myth. According to modern researches, livestock occupied a leading position in the economy of the Crimean Khanate, Crimean Khanate was one of the main wheat suppliers to the Ottoman Empire. Salt mining, viticulture and winemaking, horticulture and gardening were also developed as sources of income. When reading the history of the Crimean Tatars, it is necessary to take into account that the historical science about the Crimean Tatars is strongly influenced by Russian historians who have rewritten the history of the Crimean Khanate to justify the annexation of the Crimea in 1783, and, especially, then by Soviet historians who distorted the history of the Crimea to justify the 1944 deportation of the Crimean Tatars. In the Russian Empire 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