The Indian subcontinent, or, sometimes simply called the subcontinent, is a physiographical region in southern Asia, situated on the Indian Plate and projecting southwards into the Indian Ocean from the Himalayas. Geologically, the Indian subcontinent is related to the landmass that rifted from Gondwana and merged with the Eurasian landmass nearly 55 million years ago. Geographically, it is the peninsular region in south-central Asia, delineated by the Himalayas in the north, the Hindu Kush in the west, and the Arakanese in the east. Geopolitically, the Indian subcontinent includes all or part of Bangladesh, Bhutan, India, Nepal, Pakistan and Sri Lanka, as well as the Maldives.
According to the Oxford English Dictionary, the term "subcontinent" signifies a "subdivision of a continent which has a distinct geographical, political, or cultural identity" and also a "large land mass somewhat smaller than a continent". Its use to signify the Indian subcontinent is evidenced from early twentieth century, when most of the territory was part of British India, as it was a convenient term to refer to the region comprising both the British India and the princely states under British Paramountcy.
The Indian subcontinent as a term has been particularly common in the British Empire and its successors, while the term "South Asia" is the more common usage in Europe and North America. According to historians Sugata Bose and Ayesha Jalal, the Indian subcontinent has come to be known as South Asia "in more recent and neutral parlance." Indologist Ronald B. Inden argues that the usage of the term "South Asia" is becoming more widespread since it clearly distinguishes the region from East Asia. While "South Asia", a more accurate term that reflectes the region's contemporary political demarcations, is replacing the "Indian subcontinent", a term closely linked to the region's colonial heritage, as a cover term, the latter is still widely used in typological studies.
Since the partition of India, citizens of Pakistan (which became independent of British India in 1947) and Bangladesh (which became independent of Pakistan in 1971) often perceive the use of "Indian subcontinent" as offensive and suspicious because of the dominant placement of India in the term. As such it is being increasingly less used in those countries. Meanwhile many Indian analysts prefer to use the term because of socio-cultural commonalities of the region. The region has also been called the "Asian subcontinent", the "South Asian subcontinent", or the "Indo-Pak subcontinent", as well as India or Greater India in the classical and pre-modern sense.
Geologically, the Indian subcontinent was first a part of a largely oceanic Greater India Basin, a region of Gondwana that drifted away from East Africa about 160 million years ago, around the Middle Jurassic period. The region experienced high volcanic activity and plate subdivisions, creating Madagascar, the Seychelles, Antarctica, Australasia and the Indian subcontinent basin. The Indian subcontinent drifted northeastwards, colliding with the Eurasian plate nearly 55 million years ago, towards the end of Paleocene. The zone where the Eurasian and Indian subcontinent plates meet remains geologically active, prone to major earthquakes.
Physiographically, it is a peninsular region in south-central Asia delineated by the Himalayas in the north, the Hindu Kush in the west, and the Arakanese in the east. It extends southward into the Indian Ocean with the Arabian Sea to the southwest and the Bay of Bengal to the southeast. Most of this region rests on the Indian Plate and is isolated from the rest of Asia by large mountain barriers. Laccadive Islands, Maldives and Chagos Archipelago are three series of coral atolls, cays and faroes on the Indian plate along the Chagos–Laccadive Ridge, a submarine ridge that was generated by the northern drift of the Indian Plate over the Réunion hotspot during the Cretaceous and early Cenozoic times. The Maldives archipelago rises from a basement of volcanic basalt outpourings from a depth of about 2000 m forming the central part the ridge between Laccadives and the Great Chagos Bank.
According to anthropologist John R. Lukacs, "the Indian Subcontinent occupies the major landmass of South Asia." According to istorian B. N. Mukherjee, "The subcontinent is an indivisible geographical entity." According to geographer Dudley Stamp "there is perhaps no mainland part of the world better marked off by nature as a region or a 'realm' by itself than the Indian subcontinent."
This natural physical landmass in South Asia is the dry-land portion of the Indian Plate, which has been relatively isolated from the rest of Eurasia. The Himalayas (from Brahmaputra River in the east to Indus River in the west), Karakoram (from Indus River in the east to Yarkand River in the west) and the Hindu Kush mountains (from Yarkand River westwards) form its northern boundary. In the west it is bounded by parts of the mountain ranges of Hindu Kush, Spīn Ghar (Safed Koh), Sulaiman Mountains, Kirthar Mountains, Brahui range, and Pab range among others, with the Western Fold Belt along the border (between the Sulaiman Range and the Chaman Fault) is the western boundary of the Indian Plate, where, along the Eastern Hindu Kush, lies the Afghanistan–Pakistan border. In the east it is bounded by Patkai, Naga, Lushai and Chin hills. The Indian ocean, Bay of Bengal and Arabian Sea forms the boundary of the Indian subcontinent in the south, south-east and south-west.
Given the difficulty of passage through the Himalayas, the sociocultural, religious and political interaction of the Indian subcontinent has largely been through the valleys of Afghanistan in its northwest, the valleys of Manipur in its east, and by maritime routes. More difficult but historically important interaction has also occurred through passages pioneered by the Tibetans. These routes and interactions have led to the spread of Buddhism out of the Indian subcontinent into other parts of Asia. And the Islamic expansion arrived into the Indian subcontinent in two ways, through Afghanistan on land and to Indian coast through the maritime routes on the Arabian Sea.
In terms of modern geopolitical boundaries, the Indian subcontinent constitutes India, Pakistan, Bangladesh, Nepal, and Bhutan, besides, by convention, the island nation of Sri Lanka and other islands of the Indian Ocean, such as the Maldives. According to Chris Brewster and Wolfgang Mayrhofer, India, Pakistan, Bangladesh, Sri Lanka, Nepal and Bhutan constitute the Indian subcontinent. Brewster and Mayrhofer also maintains that with Afghanistan and Maldives included the region is referred to as South Asia. The periphery of the subcontinent, including Pakistan, Bangladesh, Kashmir and the island chains of Lakshadeep and the Maldives, features large Muslim populations, while the heartland, including most of India, Nepal and northern Sri Lanka, is overwhelmingly Hindu. Since most of these countries are located on Indian plate, a continuous landmass, the borders between two countries are often either a river or a no man's land.
The precise definition of an "Indian subcontinent" in a geopolitical context is somewhat contested as there is no globally accepted definition on which countries are a part of South Asia or the Indian subcontinent. Whether called the Indian subcontinent or South Asia, the definition of the geographical extent of this region varies. Afghanistan, despite often considered as a part of South Asia, is usually not included in the Indian subcontinent. Even when some parts of Afghanistan are sometimes included in the Indian subcontinent as a boundary territory between Central Asia and northwestern parts of the Indian subcontinent, the socio-religious history of Afghanistan is more closely related to Turkic-influenced Central Asia. The Maldives, a country consisting of a small archipelago southwest of the peninsula, while largely considered part of the Indian subcontinent, sometimes is mentioned by sources, including the International Monetary Fund, as a group of islands away from Indian subcontinent in a south-western direction.