This civilization is said to have come to an abrupt end. The following reasons are put forward for its abrupt end: The neighboring desert encroached on the fertile area and made it infertile. ... Aryan invaders killed people and destroyed the Indus Valley Civilization.

The reason for the end of Harappan Civilization are:-
1. Climate Change
2. Deforestation
3. Invasion most probably by Aryans
4. The shifting or drying up of rivers

The End of the Harappan Civilization

The Harappan civilization, also known as the Indus Valley civilization, was one of the most advanced ancient civilizations that flourished in the Indus Valley region (present-day Pakistan and northwest India) from approximately 2600 BCE to 1900 BCE. However, by around 1900 BCE, this once-prosperous civilization began to decline and eventually disappeared. The reasons for the end of the Harappan civilization are still debated among historians and archaeologists, but several theories have been put forward to explain its disappearance.

1. Environmental Changes and Natural Disasters:
One of the prominent theories suggests that environmental changes played a significant role in the decline of the Harappan civilization. It is believed that a shift in the course of the rivers, such as the Indus River, may have led to a decline in agricultural productivity, causing droughts and famine. Additionally, the occurrence of natural disasters, such as floods and earthquakes, could have further exacerbated the situation.

2. Decline in Trade and Economic System:
Another theory proposes that a decline in trade and economic activities contributed to the collapse of the Harappan civilization. The Harappans were known for their advanced urban planning, trade networks, and craftsmanship. However, it is suggested that a decline in trade routes, possibly due to environmental changes or political instability, resulted in a decline in economic prosperity. This may have led to resource scarcity, economic instability, and a breakdown of the urban system.

3. Aryan Invasion:
Some historians argue that the Harappan civilization was destroyed by an Aryan invasion. According to this theory, a group of Indo-European nomadic pastoralists known as the Aryans migrated into the region and engaged in conflict with the Harappans, ultimately leading to their downfall. However, there is limited archaeological evidence to support this theory.

4. Internal Conflict and Decline of Central Authority:
Internal conflict and a decline in central authority have also been proposed as factors contributing to the end of the Harappan civilization. The large urban centers of the civilization required effective governance and centralized administration. However, it is believed that a breakdown in the political and social order, possibly due to internal conflicts or power struggles, weakened the Harappan society and made it vulnerable to external threats.

Conclusion:
In conclusion, the end of the Harappan civilization was likely a result of multiple factors, including environmental changes, decline in trade and economic activities, internal conflicts, and possibly external invasions. The exact combination and significance of these factors remain uncertain, and further archaeological research and discoveries are necessary to gain a comprehensive understanding of the Harappan civilization's decline and disappearance.