ore humid and temperate than adjacent Siberia and Central Asia, and are home to rich temperate coniferous, broadleaf, and mixed forests, which are now mostly limited to mountainous areas, as the densely populated lowlands and river basins have been converted to intensive agricultural and urban use. East Asia's temperate forests are rich in biodiversity, with 185 tree genera compared to 53 in Europe and 99 in Eastern North America. East Asia lost fewer tree genera during the ice ages than other temperate forest regions, and retained 96 percent of the tree genera in the Pliocene fossil record while Europe retained only 27 percent. In the subtropical region of southern China and southern edge of the Himalayas, the Palearctic temperate forests transition to the subtropical and tropical forests of Indomalaya, creating a rich and diverse mix of plant and animal species. The mountains of southwest China are also designated as a biodiversity hotspot. In Southeastern Asia, high mountain ranges form tongues of Palearctic flora and fauna in northern Indochina and southern China. Isolated small outposts (sky islands) occur as far south as central Myanmar (on Nat Ma Taung, 3,050 m; 10,010 ft), northernmost Vietnam (on Fan Si Pan, 3,140 m; 10,300 ft) and the high mou