South Asia is the southern subregion of Asia, which is defined in both geographical and ethnic-cultural terms. As commonly conceptualized, the modern states of South Asia include Afghanistan, Bangladesh, Bhutan, India, the Maldives, Nepal, Pakistan, and Sri Lanka. South Asia borders East Asia to the northeast, Central Asia to the northwest, West Asia to the west and Southeast Asia to the east. Topographically, it is dominated by the Indian subcontinent and is bounded by the Indian Ocean in the south, and the Himalayas, Karakoram, and Pamir Mountains in the north.

The South Asian Association for Regional Cooperation (SAARC) is an economic cooperation organization in the region which was established in 1985 and includes all eight nations comprising South Asia. South Asia has a total area of 5.2 million sq.km (2 million sq.mi), which is 10% of the Asian continent. The population of South Asia is estimated to be 2.04 billion or about one-fourth of the world's population, making it both the most populous and the most densely populated geographical region in the world.

In 2022, South Asia had the world's largest populations of Hindus, Muslims, Sikhs, Jains, and Zoroastrians. South Asia alone accounts for 90.47% of Hindus, 95.5% of Sikhs, and 31% of Muslims worldwide, as well as 35 million Christians and 25 million Buddhists.