Final answer:
The Indus Valley civilization, a Dravidian culture, was displaced by Indo-Aryan migrations from Central Asia beginning in 1500 BCE. This Bronze Age civilization declined due to environmental factors, leading to a shift in population southward and the introduction of Vedic culture and the social caste system.
Step-by-step explanation:
The Indus Valley Civilization
It is believed that the Indus Valley civilization was a Dravidian culture whose languages are now spoken in southern India. Beginning in 1500 BCE, several Indo-Aryan migrations from Central Asia across the Hindu Kush mountains displaced the Dravidian people to southern India.
The Indus Valley Civilization, also known as the Harappan Civilization, flourished in the Indus River valley, particularly in the cities of Harappa and Mohenjo-Daro. This Bronze Age civilization enjoyed a period of prosperity thanks to its agricultural base, urban planning, and sophisticated water management systems. It is speculated that the decline of this civilization was due to environmental factors such as deforestation and declining soil productivity. After the decline, the region saw invasions by the Aryans, who brought with them social structures based on hereditary castes and the Vedic religion, which later developed into Hinduism.
Historians study this civilization through cultural artifacts, as it lacked written records. The society that thrived along the Indus River was advanced, with urban centers that displayed efficiency in their layouts and infrastructure. Settlements in present-day Afghanistan, Pakistan, and India show evidence of a well-organized society. Despite the sophisticated culture, by about 1700 BCE, these cities were abandoned, with theories suggesting environmental changes playing a major role.