The Austronesian expansion (also called the "Out of Taiwan" model) is a large-scale migration of Austronesians out of Taiwan, occurring around 3000–1500 BCE. Population growth primarily fueled this migration. These first settlers landed in northern Luzon in the archipelago of the Philippines, intermingling with the earlier Australo-Melanesian population who had inhabited the islands since about 23,000 years earlier. Over the next thousand years, Austronesian peoples migrated southeast to the rest of the Philippines, and into the islands of the Celebes Sea, Borneo, and Indonesia. The Austronesians that spread westward through Maritime Southeast Asia also colonized parts of mainland Southeast Asia.