Sundaland

Sundaland is a biogeographical region of Southeast Asia that encompasses the Malay Peninsula and the western Indonesian archipelago, including the islands of Sumatra, Java, and Borneo, together with the submerged continental shelves that connect them during periods of low sea level. The term is used to describe a former contiguous landmass and the distinct flora and fauna that evolved there, as well as the landmasses that subsequently became isolated island ecosystems.

Geologically, Sundaland relates to fluctuations in sea level during the Pleistocene. At the Last Glacial Maximum, roughly 26,000 to 19,000 years ago, global sea level was about 120 meters lower than today, exposing the Sunda Shelf. This created land bridges between mainland Southeast Asia and the western Indonesian islands, facilitating the dispersal of plants and animals and shaping the region’s rich but regionally distinct biodiversity. When sea levels rose again, these connections were submerged, leaving the present-day islands with their characteristic insularity.

Biogeographically, Sundaland hosts tropical rainforest ecosystems that remain some of the planet’s most biodiverse. The region is notable for orangutans on Sumatra and Borneo, diverse primates, endemic birds, and a canopy of dipterocarp forests. The biodiversity is especially high on Borneo and Sumatra, though many habitats are threatened by deforestation, logging, and agricultural conversion.

In human prehistory, Sundaland and its surrounding areas were significant corridors during low sea levels, influencing patterns of migration and settlement in Southeast Asia. Fossil finds in Java (Homo erectus) and in other parts of the broader region underscore the long-standing human presence and the complex geography of dispersal that followed the rising seas. The boundaries of Sundaland vary by field, and the term primarily reflects paleo-geographic and biogeographic concepts rather than a political entity.