South Asian ethnic groups are an ethnolinguistic grouping of the diverse populations of South Asia, including the nations of India, Pakistan, Bangladesh, Nepal, Bhutan, the Maldives, and Sri Lanka. While Afghanistan is variously considered to be part of both Central Asia and South Asia, Afghans are generally not included among South Asians. The majority of the population fall within three large linguistic groups: Indo-Aryan, Dravidian, and Iranic. The Indian, Nepalese, and Sri Lankan societies are traditionally divided into castes or clans, which are based primarily on labour divisions; these categories have had no official status in India since independence in 1947, except for the scheduled castes and tribes, which remain registered for the purpose of affirmative action. In today's India, the population is categorised in terms of the 1,652 mother tongues spoken. These groups are also further subdivided into numerous sub-groups, castes and tribes. Indo-Aryans form the predominant ethnolinguistic group in India (North India, East India, West India, and Central India), Bangladesh, Pakistan, Nepal, Sri Lanka, and the Maldives. Dravidians form the predominant ethnolinguistic group in southern India, the northern and eastern regions of Sri Lanka and a small pocket of Pakistan. The Iranic peoples also have a significant presence in South Asia, the large majority of whom are located in Pakistan. Minority groups not falling within either large group mostly speak languages belonging to the Austroasiatic and Tibeto-Burman language families, and largely live around Ladakh and Northeast India, Nepal, Bhutan, and the Chittagong Hill Tracts of Bangladesh. The Andamanese (Sentinel, Onge, Jarawa, and Great Andamanese) live in some of the Andaman Islands and speak a language isolate, as do the Kusunda in central Nepal, the Vedda in Sri Lanka, and the Nihali of Central India, who number about 5,000 people. The people of the Hunza Valley in Pakistan are another distinct population; they speak Burushaski, a language isolate. The traditions of different ethnic groups in South Asia have diverged, influenced by external cultures, especially in the northwestern parts of South Asia and also in the border regions and busy ports, where there are greater levels of contact with external cultures. There is also a lot of genetic diversity within the region. For example, most of the ethnic groups of the northeastern parts of South Asia are genetically related to peoples of East or Southeast Asia. There are also genetically isolated groups who have not been genetically influenced by other