In the early years of the 20th century, during the Russian Civil War, many Siberian tigers were killed when tiger hunting was legal. In addition, the tigers' habitat was disrupted by the building of railroads across eastern Russia. By the 1940s, only 40 Siberian tigers remained in the wild and they faced almost certain extinction, Fortunately, in 1947 the Soviet Union banned tiger hunting in protected zones and strictly enforced the law. As a result, the tiger population rebounded to several hundred.