Lombok Strait
To the east, the Lombok Strait separates Bali from Lombok and marks the biogeographical division between the fauna of the Indomalayan realm and the distinctly different fauna of Australasia. The transition is known as the Wallace Line, named after Alfred Russel Wallace, who first proposed a transition zone between these two major biomes. When sea levels dropped during the Pleistocene ice age, Bali was connected to Java and Sumatra and to the mainland of Asia and shared the Asian fauna, but the deep water of the Lombok Strait continued to keep Lombok Island and the Lesser Sunda archipelago isolated.