The history of India begins with evidence of human activity of Homo sapiens as long as 75,000 years ago, or with earlier hominids including Homo erectus from about 500,000 years ago. The Indus Valley Civilization, which spread and flourished in the northwestern part of the Indian subcontinent from c. 3300 to 1300 BCE in present-day Pakistan and northwest India, was the first major civilization in South Asia. A sophisticated and technologically advanced urban culture developed in the Mature Harappan period, from 2600 to 1900 BCE. This Bronze Age civilization collapsed before the end of the second millennium BCE and was followed by the Iron Age Vedic Civilization, which extended over much of the Indo-Gangetic plain and which witnessed the rise of major polities known as the Mahajanapadas. In one of these kingdoms, Magadha, Mahavira and Gautama Buddha were born in the 6th or 5th century BCE and propagated their śramanic philosophies.
Most of the subcontinent was conquered by the Maurya Empire during the 4th and 3rd centuries BCE. It became fragmented, with various parts ruled by numerous Middle kingdoms for the next 1,500 years. This is known as the classical period of Indian history, during which time India has sometimes been estimated to have had the largest economy of the ancient and medieval world, with its huge population generating between one fourth and one third of the world's income up to the 18th century. Much of northern and central India was united in the 4th century CE, and remained so for two centuries, under the Gupta Empire. This period, witnessing a Hindu religious and intellectual resurgence, is known as the "Golden Age of India". From this time, and for several centuries afterwards, southern India, under the rule of the Chalukyas, Cholas, Pallavas, and Pandyas, experienced its own golden age. During this period, aspects of Indian civilization, administration, culture, and religion (Hinduism and Buddhism) spread to much of Asia.