During what geologists call the Pleistocene Age (roughly 1.75 million years ago to 10,000 B.C.), the falling and rising of the world's sea levels left Taiwan alternately connected to and isolated from the mainland of China. Although early hominids (Homo erectus) are establishing themselves in parts of China during most of this time, for whatever reason none of these appear to move onto Taiwan until near the end of this period. Some scientists claim to find signs of human presence on Taiwan as early as 50,000 B.C.; if this is so, these hominids (possibly archaic Homo sapiens) get there by walking across a land bridge when the sea level is low. The first undisputed signs of hominids' occupation of Taiwan date from c. 10,000 B.C., by which time they are full-fledged Homo sapiens. By at least 6000 B.C. the sea level has risen to its present level, leaving Taiwan completely isolated from the mainland and with essentially its presentday physical characteristics.
Sometime thereafter—at least by about 4000 B.C.—new groups of Southern Mongoloids begin to move over to Taiwan; the main theory is that they come from southern China, although others believe that they come from the islands or mainland of Southeast Asia. In any case, from this point on the inhabitants of Taiwan pass through the cultural phases similar to those throughout East and Southeast Asia—specifically, those classed under Neolithic. Meanwhile, by at least 2800 B.C. some inhabitants of Taiwan appear to move out via boats to settle other Pacific islands, first the Philippines and then Indonesia. As a result, Taiwan remains receptive to some of the foods and other artifacts imported from their relatives around Southeast Asia and the Pacific. Taiwan, however, remains something of a backwater culture in relation to other places throughout East and Southeast Asia. Although there are legendary claims to Chinese contacts with Taiwan during the first millennium A.D., not until about A.D. 1000 will a new infusion of Chinese begin to pull Taiwan into the mainstream of Asian history.