The Indus Valley Civilization was one of the earliest civilizations in South Asia, developing around 4,500-5,000 years ago along the Indus River valley. Excavations in Harappa and Mohenjo-Daro revealed well-planned cities with multi-storied brick houses, bathrooms, and drainage systems, suggesting a complex society that accumulated great wealth as traders. The Indus Valley people were likely Dravidians who farmed along the river and depended on seasonal floods for irrigation. While the civilization declined suddenly around 1750 BCE for unknown reasons, it provides evidence of an advanced Bronze Age culture in the Indian subcontinent.