What happened to the ancient peoples of the Indus Valley?

The Indus Valley Civilization declined around 1900 BCE, long before the Gupta Empire, so the Guptas did not destroy it. There is no evidence that its people migrated to Greece and Rome or were wiped out by a fourth-century tsunami. The civilization’s decline is linked to changes such as shifting rivers and a drier climate, but its exact causes remain uncertain; this matches the choice saying the cause remains unknown.

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