All animal life that lives in a particular geographic area during a particular time in history. The type of fauna to be found in any particular region is determined by factors such as plant life, physical environment, topographic barriers, and evolutionary history. Zoologists sometimes divide the earth into six regions inhabited by distinct faunas: Ethiopian (Africa south of the Sahara, Madagascar, Arabia), Neotropical (South and Central America, part of Mexico, the West Indies), Australian (Australia, New Zealand, New Guinea), Oriental (Asia south of the Himalaya Mountains, India, Sri Lanka, Malay Peninsula, southern China, Borneo, Sumatra, Java, the Philippines), Palearctic (Europe, Asia north of the Himalaya Mountains, Afghanistan, Iran, North Africa), and Nearctic (North America as far south as southern Mexico).