The Indus Valley Civilization (IVC), also known as the Harappan Civilization, is a Bronze Age cultural and political entity that represents the earliest known urban culture of the Indian subcontinent. It is a concept in history and archaeology, not an act, institution, or scheme.
The civilization originated from earlier Neolithic cultures, such as those at Mehrgarh, and its entire span is generally dated from c. 3300 BCE to c. 1300 BCE. The Mature Harappan Phase, which saw the rise of its great cities, lasted from c. 2600 BCE to c. 1900 BCE. It emerged in the alluvial plain of the Indus River and the now-seasonal Ghaggar-Hakra river system, spanning much of modern-day Pakistan, northwestern India, and northeast Afghanistan.
The IVC is characterized by sophisticated urban planning, with cities like Harappa and Mohenjo-daro built on a rectilinear grid pattern with streets intersecting at right angles. Its mechanism of operation included a strong municipal administration, evidenced by elaborate drainage systems, baked brick houses, and public water management structures like the Great Bath. The economy was based on agriculture, producing crops like wheat, barley, and cotton, and extensive trade, with standardized weights and seals found in distant regions like Mesopotamia (Sumer). The civilization used a pictographic script on seals, which remains undeciphered.
The IVC connects to contemporary civilizations like Ancient Egypt and Mesopotamia, being one of the three earliest and the most widespread of the ancient world's civilizations. It is also linked to the later cultures of the Indian subcontinent, with its farming innovations and urban designs influencing subsequent developments.
Recent research has significantly changed the understanding of its decline, replacing the discredited "Aryan Invasion Theory". New scientific evidence, including climate reconstructions, suggests the civilization did not suffer a sudden collapse but rather a gradual transformation and deurbanization between c. 1900 BCE and c. 1500 BCE. This change was primarily driven by a series of century-long droughts and the failure of the summer monsoon, which caused populations to shift toward the Indus River and adopt a more village-based lifestyle. The core features of its urban planning and undeciphered script remain the same, but the narrative has shifted from a sudden collapse to a resilient, adaptive society facing long-term environmental stress.