The European bison (Bison bonasus), the largest of the continent's land mammals, died out in the late Middle Ages. Slovakia retains no exact data on its extinction in the 15th century, and only toponyms such as Zuberec, Zubrohlava and Zubrá indicate its original distribution, zubor being the Slovak name for the animal. It survived into the twentieth century in the wild only in Poland and Caucasia. As its world population has reached somewhat over 2,000, it is listed in the IUCN Red Book as a protected species. The preservation of the bison is Europe's greatest achievement in animal protection. Its reintroduction into Slovakia came about in 1957 with the establishment of a breeding station on 27 hectares of land near Topoľčianky, intended for twelve animals, but now accommodating annually between twenty and twenty-five. So far the station has reared more than seventy bison, which have been used in zoos and for research and educational purposes. They are strictly protected. Consideration is being given to releasing bison into the wild in the area of the Starina dam in East Slovakia.