George Windsor Earl the Physical Geography of South-Eastern Asia and Australia", published in 1845, described how shallow seas connected islands on the west (Sumatra, Java, etc.) with the Asian continent and with similar wildlife, and islands on the east such as New Guinea were connected to Australia and were characterised by the presence of marsupials. This formed the insipiration for Alfred Russel Wallace to propose the faunal boundary line now known as the Wallace Line. He published a paper in 1850 that invented the term 'Indu-nesians', for a quaint racial classification, derived from the Latin for India and island. He published a seminal
Sundaland Russel Wallace as the eastern boundary of the range of Asia's land mammal fauna, and thus the boundary of the Indomalaya and Australasia ecozones. The islands east of the Wallace line are known as Wallacea, a separate biogeographical region that is considered part of Australasia. The Wallace Line corresponds to a deep-water channel that has never been crossed by any land bridges. The northern border of Sundaland is more difficult to define in bathymetric terms; a phytogeographic transition at approximately 9ºN is considered to be the northern boundary. Greater portions of Sundaland were most recently exposed during the last glacial