According to the IUCN (2013), 13 species are currently recognized in the taxonomic group to which wild cattle belong (tribe Bovini): aurochs (now only represented by domestic breeds), banteng (in Southeast Asia), gaur (in India and mainland Southeast Asia), kouprey (in northern and eastern Cambodia and adjacent countries), yak (throughout the Tibetan Plateau), American bison (in the western half of North America), European bison (now confined to Eastern Europe), African buffalo (in sub-Saharan Africa), Asian water buffalo (only a few small populations in India and mainland Southeast Asia), lowland anoa and mountain anoa (both found only on Sulawesi and Buton Island), tamaraw (endemic to the Philippine island of Mindoro) and saola (in the Annamite Mountains of Vietnam and Laos).
The most fascinating aspect in the evolution of Bovini is that at least five species have been domesticated during the Holocene: aurochs, banteng, gaur, yak, Asian buffalo, and maybe the kouprey. As a result, their recent evolutionary history has been severely disrupted by the migration and explosive growth of human populations throughout the world. Before the Neolithic, populations of wild cattle were very successful and widely distributed across Europe, Africa, Asia and North America. Today, most wild species are restricted to small and isolated populations in a few countries, whereas domestic forms are present on all arable land on Earth. The aurochs, which was the ancestor of most breeds of domestic cattle, became extinct in 1627 (Tikhonov 2008). Field scientists have reported no living specimen of kouprey in the open deciduous dipterocarp forests of Southeast Asia since the 1980s, suggesting that it is possibly extinct (Timmins et al. 2008). All other wild species but the American bison are listed as Critically Endangered (CR), Endangered (EN) or Vulnerable (VN) in the IUCN Red List of Threatened Species (IUCN 2013).