<Li> <P> 1890 map of Asia </P> </Li> <P> 1890 map of Asia </P> <P> Asia is the largest continent on Earth . It covers 9% of the Earth's total surface area (or 30% of its land area), and has the largest coastline, at 62,800 kilometres (39,022 mi). Asia is generally defined as comprising the eastern four - fifths of Eurasia . It is located to the east of the Suez Canal and the Ural Mountains, and south of the Caucasus Mountains (or the Kuma--Manych Depression) and the Caspian and Black Seas . It is bounded on the east by the Pacific Ocean, on the south by the Indian Ocean and on the north by the Arctic Ocean . Asia is subdivided into 48 countries, three of them (Russia, Kazakhstan and Turkey) having part of their land in Europe . </P> <P> Asia has extremely diverse climates and geographic features . Climates range from arctic and subarctic in Siberia to tropical in southern India and Southeast Asia . It is moist across southeast sections, and dry across much of the interior . Some of the largest daily temperature ranges on Earth occur in western sections of Asia . The monsoon circulation dominates across southern and eastern sections, due to the presence of the Himalayas forcing the formation of a thermal low which draws in moisture during the summer . Southwestern sections of the continent are hot . Siberia is one of the coldest places in the Northern Hemisphere, and can act as a source of arctic air masses for North America . The most active place on Earth for tropical cyclone activity lies northeast of the Philippines and south of Japan . The Gobi Desert is in Mongolia and the Arabian Desert stretches across much of the Middle East . The Yangtze River in China is the longest river in the continent . The Himalayas between Nepal and China is the tallest mountain range in the world . Tropical rainforests stretch across much of southern Asia and coniferous and deciduous forests lie farther north . </P>

How many countries are in the asia continent