And it happened at least 3000 years ago, most certainly was natural, and there wasn’t a damn thing they could have done to stop it.
The Indus or Harappan Civilization was one of the greatest societies in the ancient world. Contemporary with Ancient Egypt and Mesopotamia, its population is thought to have made up 10% of the world at one point. Yet, between 3900 and 3000 years ago, the cities crumbled and the people disappeared. What went wrong, and what can we learn from its demise?
Basically the monsoons were too heavy, then as they declined they became just right, and then they declined too much.