Understanding the historical biogeography of this global biodiversity hotspot is as important to long-term conservation goals as ecology and evolution are to understanding current patterns and processes. Todays geography is, however, misleading and typical of only ~2% of the last million years
>90% of that time the regions land area was 1.52.0 times larger as mean sea levels were 62 m below todays, climates were cooler, and extensive forests and savanna covered the emerged Sunda plains. The regions land area varied two-fold as sea levels fluctuated up to ±50 m with each of ~50 Pleistocene glacial cycles, and forests expanded and contracted with oscillations in land area and seasonality. This dynamic geographic history is relevant to the development of biogeographic regionalism and shows that it is todays forests that are refugial, not those of the Last Glacial Maximum. This history affects how species will adapt or shift their ranges in response to global warming and further decreases in land area (submergence of low-lying coastal areas) during the 21st century. The alternative is mass species extinction. The biota is also threatened by the continued destruction of forest, destruction of Mekong River flood-pulse based ecosystems, and continued human population growth. Human biogeography will become more important in conservation planning as tens of millions of people who depend on protected area forests, riverine ecosystems, and coastal habitats become environmental refugees. Conservation scientists need to become more involved in regional ecological education, environmental stewardship, and ecosystem-based adaptation to sustain as much as possible of this rich biota and the ecological services it provides.