Stone age rock shelters with paintings at the Bhimbetka rock shelters in Madhya Pradesh are the earliest known traces of human life in India. The first known permanent settlements appeared over 9,000 years ago and gradually developed into the Indus Valley Civilization, dating back to 3300 BCE in western India. It was followed by the Vedic period, which laid the foundations of Hinduism and other cultural aspects of early Indian society, and ended in the 500s BC. From around 550 BCE, many independent kingdoms and republics known as the Mahajanapadas were established across the country.

The empire built by the Maurya Empire under Emperor Ashoka united most of South Asia in the third century BCE. From 180 BCE, a series of invasions from Central Asia followed, including those led by the Indo-Greeks, Indo-Scythians, Indo-Parthians and Kushans in the north-western Indian subcontinent. From the third century CE, the Gupta dynasty oversaw the period referred to as ancient "India's Golden Age." Among the notable South Indian empires were the Chalukyas, Rashtrakutas, Hoysalas, Pallavas, Pandyas, and Cholas. Science, engineering, art, literature, astronomy, and philosophy flourished under the patronage of these kings.

Following invasions from Central Asia between the tenth and twelfth centuries, much of north India came under the rule of the Delhi Sultanate, and later the Mughal Empire. Mughal emperors gradually expanded their Kingdoms to cover large parts of the subcontinent. Nevertheless, several indigenous kingdoms, such as the Vijayanagara Empire, flourished, especially in the south. In the seventeenth and eighteenth century, the Mughal supremacy declined and the Maratha Empire became the dominant power.

From the sixteenth century, several European countries, including Portugal, the Netherlands, France, and the United Kingdom, started arriving as traders and later took advantage of the fractious nature of relations between the kingdoms to establish colonies in the country. By 1856, most of India was under the control of the British East India Company. A year later, a nationwide insurrection of rebelling military units and kingdoms, variously referred to as the First War of Indian Independence or Sepoy Mutiny, seriously challenged British rule but eventually failed. As a consequence, India came under the direct control of the British Crown as a colony of the British Empire.

During the first half of the twentieth century, a nationwide struggle for independence was launched by the Indian National Congress and other political organizations. In the 1920s and 1930, a movement led by Mahatma Gandhi, and displaying commitment to ahimsa, or non-violence, millions of protesters engaged in mass campaigns of civil disobedience. Finally, on 15 August 1947, India gained independence from British rule, but was partitioned with independent governments for the Dominion of India and the Dominion of Pakistan in accordance to wishes of the Muslim League, along the lines of religion to create the Islamic nation state of Pakistan. Three years later, on 26 January 1950, India became a republic and a new constitution came into effect.

Since independence, India has experienced sectarian violence and insurgencies in various parts of the country, but has maintained its unity and democracy. It has unresolved territorial disputes with China, which in 1962 escalated into the brief Sino-Indian War and with Pakistan, which resulted in wars in 1947, 1965, 1971, and 1999. India is a founding member of the Non-Aligned Movement and the United Nations (as part of British India). In 1974, India conducted an underground nuclear test. This was followed by five more tests in 1998, making India a nuclear state. Beginning in 1991, significant economic reforms have transformed India into one of the fastest-growing economies in the world, adding to its global and regional clout.