One-third the area of the United States, the Republic of India occupies most of the subcontinent of India in southern Asia. It borders on China in the northeast. Other neighbors are Pakistan on the west, Nepal and Bhutan on the north, and Burma and Bangladesh on the east.
The country can be divided into three distinct geographic regions: the Himalayan region in the north, which contains some of the highest mountains in the world, the Gangetic Plain, and the plateau region in the south and central part. Its three great river systems—the Ganges, the Indus, and the Brahmaputra—have extensive deltas and all rise in the Himalayas.
One of the earliest civilizations, the Indus Valley civilization flourished on the Indian subcontinent from c. 2600 B.C. to c. 2000 B.C. It is generally accepted that the Aryans entered India c. 1500 B.C. from the northwest, finding a land that was already home to an advanced civilization. They introduced Sanskrit and the Vedic religion, a forerunner of Hinduism. Buddhism was founded in the 6th century B.C. and was spread throughout northern India, most notably by one of the great ancient kings of the Mauryan dynasty, Asoka (c. 269–232 B.C. ), who also unified most of the Indian subcontinent for the first time.
In 1526, Muslim invaders founded the great Mogul Empire, centered on Delhi, which lasted, at least in name, until 1857. Akbar the Great (1542–1605) strengthened and consolidated this empire. The long reign of his great-grandson, Aurangzeb (1618–1707), represents both the greatest extent of the Mogul Empire and the beginning of its decay.