Indus Valley Civilization Emerges
Around 3500 BCE, farming communities in the Indus River basin and its surroundings, in what is now Pakistan and northwestern India, were beginning the long transformation that would produce one of the world's earliest urban societies. The Indus Valley Civilization, also called the Harappan Civilization, is notable for its carefully planned cities, sophisticated water management, and standardized trade goods. Its fully urban phase came much later, around 2600 BCE, so the date given here marks the early roots of the tradition rather than the cities themselves.
The background lies in the villages of the greater Indus region, where people had farmed wheat and barley and herded cattle, sheep, and goats since roughly 7000 BCE, as at the site of Mehrgarh in Balochistan. Over the following millennia, settlements grew, crafts such as pottery and bead-making became more specialized, and regional networks of exchange expanded. Archaeologists often call the stages leading up to the mature civilization the Early Harappan or Pre-Harappan phases. The fertile floodplains of the Indus and the now-vanished Ghaggar-Hakra river system supported rising populations.
By the mature phase, from about 2600 to 1900 BCE, cities such as Harappa and Mohenjo-daro had emerged, along with others like Dholavira, Ganweriwala, and Rakhigarhi. Many were laid out on grid-like street plans, and buildings were often made of uniform baked bricks. Houses commonly had private wells and bathing areas, with covered drains running beneath the streets, a level of urban sanitation unmatched in much of the ancient world. Mohenjo-daro's so-called Great Bath is a striking structure, though its exact purpose, whether ritual or practical, remains uncertain.
The civilization also produced standardized weights, finely made beads, and thousands of carved stamp seals bearing animals and a still-undeciphered script. Its merchants traded with Mesopotamia, as shown by Indus-style objects found there and by Mesopotamian references to a land called Meluhha, which many scholars identify with the Indus region. Notably, excavations have revealed few obvious palaces or monumental tombs, leading to debate about how the society was governed and how much social inequality existed.
From about 1900 BCE, the cities declined and many were gradually abandoned. Explanations include shifting monsoon patterns, changing river courses, and weakening trade links, though no single cause is firmly established. The once-popular idea of a sudden invasion is now widely doubted. Rediscovered by modern archaeologists in the 1920s, the civilization showed that South Asia was home to a major early urban culture, and some of its craft traditions and town-planning ideas may have echoed in later societies, though the connections remain debated.