Vietnam is located on the eastern part of the Southeast Asian mainland. The area was populated as early as the Paleolithic, and in the first millennium BC, states were established in what is now northern Vietnam, in the Red River Delta. From 111 BC, the Han dynasty annexed North and Central Vietnam under Chinese rule until the emergence of the First Dynasty in 939 BC. The successive ruling dynasties embraced Chinese influences via Confucianism and Buddhism, and extended south to the Mekong Delta, eventually conquering Champa. For most of the 17th and 18th centuries, Vietnam was divided into two domains. Its territory was annexed to French Indochina as three separate regions in 1887. Just after World War II, the Viet Minh, a nationalist coalition, launched the August Revolution and in 1945 declared Vietnam's independence. Vietnam suffered a long period of warfare in the 20th century. Following the victory of the North Vietnamese in the Vietnam War in 1975, the country was reunified as a unitary socialist state under the Communist Party of Vietnam in 1976. Because it is located in the Indomalayan realm, the country is one of only twenty-five countries with a uniquely high level of biodiversity. In terms of biodiversity, it ranks 16th in the world, home to around 16% of the world's species. The country has 15 986 plant species of which 10% are endemic. Vietnam is home to 260 reptile and 120 amphibian species, and 840 birds and 310 mammals, of these 100 birds and 78 mammals are endemic. The country has two natural World Heritage Sites, Hạ Long Bay and Phong Nha-Kẻ Bàng National Park, and nine biosphere reserves.