The Indian subcontinent is a physiographical region in Southern Asia, situated on the Indian Plate, projecting southwards into the Indian Ocean from the Himalayas. Geopolitically, it spans major landmasses from the countries of Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, and Sri Lanka. Although the terms "Indian subcontinent" and "South Asia" are often used interchangeably to denote the region, the geopolitical term of South Asia frequently includes Afghanistan, which is not considered part of the subcontinent.
Geologically, the subcontinent originates from Insular India, an isolated landmass that rifted from the supercontinent of Gondwana during the Cretaceous and merged with the landmass of Eurasia nearly 55 million years ago, forming the Himalayas. Historically, as well as to the present day, it is and has been the most populated region in the world, holding roughly 20–25 percent of the global population at all times in history. Geographically, it is the peninsular region in South Asia, delineated by the Himalayas in the north, the Hindu Kush in the west, and the Arakan in the east. The neighboring geographical regions around the subcontinent include the Tibetan Plateau to the north, the Indochinese Peninsula to the east, and the Iranian Plateau to the west and the Indian Ocean to the south.
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 the early twentieth century when most of the territory was either part of the British Empire or allied with them. It was a convenient term to refer to the region comprising both British India and the princely states.
The 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.