The Alaska Purchase (Prodazha Alyaski) was the United States' acquisition of Alaska from the Russian Empire. Alaska was formally transferred to the United States on October 18, 1867, through a treaty ratified by the United States Senate. Russia had established a presence in North America during the first half of the 18th century, but few Russians ever settled in Alaska. In the aftermath of the Crimean War, Russian Tsar Alexander II began exploring the possibility of selling Alaska, which, in any future war, would be difficult to defend from being conquered by Russia's archrival, the United Kingdom of Great Britain and Ireland. Following the end of the American Civil War, US Secretary of State William Seward entered into negotiations with Russian minister Eduard de Stoeckl for the purchase of Alaska. Seward and Stoeckl agreed to a treaty on March 30, 1867, and the treaty was ratified by the United States Senate by a wide margin. The purchase added of new territory to the United States for the cost of million in or $ per acre. Reactions to the purchase in the United States were mostly positive, as many believed possession of Alaska would serve as a base to expand American trade in Asia. Some opponents labeled the purchase as "Seward's Folly", or "Seward's Icebox", as they contended that the United States had acquired useless land. Nearly all Russian settlers left Alaska in the aftermath of the purchase; Alaska would remain sparsely populated until the Klondike Gold Rush began in 1896. Originally organized as the Department of Alaska, the area was renamed the District of Alaska (1884) and the Alaska Territory (1912) before becoming the modern State of Alaska in 1959. Russian America was settled by promyshlenniki, merchants and fur trappers who expanded through Siberia. They arrived in Alaska in 1732, and in 1799 the Russian-American Company (RAC) received a charter to hunt for fur. No colony was established, but the Russian Orthodox Church sent missionaries to the natives and built churches.