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 Bangladesh, Bhutan, India, Maldives, Nepal 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.
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. There are numerous languages in South Asia. The spoken languages of the region are largely based on geography and shared across religious boundaries, but the written script is sharply divided by religious boundaries.
The Nagari script has been the primus inter pares of the traditional South Asian scripts. The Devanagari script is used for over 120 South Asian languages,including Hindi,Marathi, Nepali, Pali, Konkani, Bodo, Sindhi and Maithili among other languages and dialects, making it one of the most used and adopted writing systems in the world. The largest spoken language in this region is Hindustani language, followed by Bengali, Telugu, Tamil, Marathi, Gujarati, Kannada, and Punjabi. In the modern era, new syncretic languages developed in the region such as Urdu that are used by the Muslim community of northern South Asia (particularly Pakistan and northern states of India). English, with British spelling, is commonly used in urban areas and is a major economic lingua franca of South Asia.