During the third and second millennia B.C., the Harappan civilization (also called the Indus Valley civilization) flourished throughout northern India. This culture developed a regular system of town planning, as seen in two great cities at Harappa and Mohenjo Daro. The Harappan remains include carnelian beads, terracotta and bronze statuettes (such as the bronze “dancing girl” from Mohenjo Daro), as well as seals depicting animals and inscribed with a script that has not yet been deciphered.

The Harappan civilization came to an end in the early second millennium B.C. The following period is often called a dark age by scholars, because little of it has survived in the archaeological record. One small group of objects, the Diamadabad Bronzes (c. 1500–1050 B.C.), has been found in western India. These bronzes—consisting of oxen, a rhinoceros, a buffalo and an elephant—suggest that the so-called dark age may in fact have supported vigorous artistic traditions, if only in media like wood that do not survive in damp climates.

This was also the period in which the stories, poems and songs that would form the basis of Hinduism were composed as part of an oral tradition. The Vedic poems (including the sacred Rig-Veda, a collection of ritual hymns) and the major Hindu epics, the Mahabharata and Ramayana, were memorized and passed down from generation to generation, only to be recorded in writing much later.

In 516 B.C., the Persian Empire conquered northwest India. Many of the Persian battles were fought by Greek mercenaries; the Greeks who remained in India after the wars came to be known as Indo-Greeks. The northwest never became part of mainstream Indian culture; orthodox Brahmins branded it impure for having been under the domination of the Persians, no matter how brief their presence.

Alexander conquered the region in 327 B.C., though the extent of his influence on India is a matter of debate: No reference to Alexander has been found in any ancient work of Indian literature. In any event, shortly after Alexander’s departure, Chandragupta Maurya rose to power, founded an empire, and became the first ruler of a united India.