Which environmental changes may have contributed to the decline of the Indus civilization?

While there is no scholarly consensus on the exact cause of the decline of the Indus civilization, environmental factors are considered a primary theory for the breakdown of its urban society. These environmental changes may have contributed to the civilization's collapse in several ways:

• Climatic Shifts: A weakening of the Indian Ocean monsoon over the last 4,000 to 6,000 years led to increased aridity in the region, which likely caused agricultural disasters and undermined the resource base that supported these urban centers.12
• Resource Stress: Population growth and the overexploitation of natural resources may have placed excessive environmental stress on the land, exacerbating the impact of changing climatic patterns.1
• Tectonic and Hydrological Events: Some researchers suggest that sudden, catastrophic events—such as tectonic shifts—may have caused the Saraswati River to dry up or triggered severe flooding, as evidenced by the deep flood deposits found at Mohenjo-daro.31
• River Migration: Historical and physiographic evidence indicates that the Indus River and its tributaries frequently shifted their courses, which would have significantly disrupted the established agricultural and trade systems of the civilization.4

It is widely believed that a complex interaction of these natural forces weakened the social fabric, leaving the civilization vulnerable to further decline.1