South Asia or Southern Asia is the southern region of the Asian continent, which comprises the sub-Himalayan countries and, for some authorities, also includes the adjoining countries to the west and the east. Topographically, it is dominated by the Indian Plate, which rises above sea level as the Indian subcontinent south of the Himalayas and the Hindu Kush. South Asia is bounded on the south by the Indian Ocean and on land (clockwise, from west) by West AsiaCentral AsiaEast Asia, and Southeast Asia.

Different sources vary in their statements of which nations are part of the region. For example, according to the United Nations geographical region classification,[1] Southern Asia comprises the countries of AfghanistanBangladeshBhutanIndiaIranMaldivesNepalPakistan, andSri Lanka. However, the United Nations notes that the "assignment of countries or areas to specific groupings is for statistical convenience and does not imply any assumption regarding political or other affiliation of countries or territories."[2] By some definitions, some of those nations are not part of the region, and by some definitions, Burma and Tibet are also included in the region (see below).

South Asia is home to well over one fifth of the world's population, making it both the most populous and the most densely populated geographical region in the world.[3] The South Asian Association for Regional Cooperation is an economic cooperation organisation in the region.