South Asia, also known as Southern Asia or the Indian Subcontinent, is the southern region of the Asian continent, which comprises the sub-Himalayan countries and, for some authorities (see below), 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 surrounded (clockwise, from west) by Western Asia, Central Asia, Eastern Asia, Southeastern Asia and the Indian Ocean.

According to the United Nations geographical region classification, Southern Asia comprises the countries of Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, and Sri Lanka. By other definitions and interpretations (see below), Afghanistan, Burma, Iran, and Tibet are also sometimes included in the region of South Asia. South Asia is home to well over one fifth of the world's population, making it both the most populous and most densely populated geographical region in the world. The South Asian Association for Regional Cooperation is an economic cooperation organization in the region.