Sundaland

Sundaland (also called the Sundaic region) is a biogeographical region of Southeastern Asia which encompasses the Sunda shelf, the part of the Asian continental shelf that was exposed during the last glacial period of the , from approximately 110,000 to 12,000 years ago. It includes the Malay Peninsula Malaysia on the Asian mainland, as well as the large islands of Borneo, Java, and Sumatra and their surrounding islands.

The eastern boundary of Sundaland is the Wallace Line, identified by Alfred 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, and are considered part of Australasia.

The South China Sea and adjoining landmasses had been investigated by scientists such as Molengraaff and Umbgrove, who had postulated ancient, now submerged, drainage systems. These were mapped by Tjia in 1980 and described in greater detail by Emmel and Curray in 1982 complete with river deltas, floodplains and backswamps. The ecology of the exposed Sunda shelf has been investigated by analyzing cores drilled into the ocean bed. The pollens found in the cores have revealed a complex ecosystem that changed over time.

The flooding of Sundaland separated species that had once shared the same environment such as the river threadfin (Polydactylus macrophthalmus, Bleeker 1858), that had once thrived in a river system now called "North Sunda River" or "Molengraaff river". The fish is now found in the Kapuas River on the island of Borneo, and in the Musi and Batanghari rivers in Sumatra.

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