"South Asia is the southern region of Asia, which is defined in both geographical and ethno-cultural terms. The region consists of the countries of Afghanistan, Pakistan, India, Nepal, Bhutan, Bangladesh, the Maldives, and Sri Lanka. Topographically, it is dominated by the Indian Plate and defined largely by the Indian Ocean on the south, and the Himalayas, Karakoram, and Pamir mountains on the north. The Amu Darya, which rises north of the Hindu Kush, forms part of the northwestern border. On land (clockwise), South Asia is bounded by Western Asia, Central Asia, East Asia, and Southeast Asia.
The South Asian Association for Regional Cooperation (SAARC) is an economic cooperation organisation in the region which was established in 1985 and includes all eight nations comprising South Asia. South Asia covers about 5.2 million km2 (2.0 million sq mi), which is 11.71% of the Asian continent or 3.5% of the world's land surface area. The population of South Asia is about 1.891 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. Overall, it accounts for about 39.49% of Asia's population, over 24% of the world's population, and is home to a vast array of people.
In 2010, South Asia had the world's largest populations of Hindus, Muslims, Sikhs, Jains and Zoroastrians. South Asia alone accounts for 98.47% of Hindus, 90.5% of Sikhs, and 31% of Muslims worldwide, as well as 35 million Christians and 25 million Buddhists."