Final answer:
The Aryans were the warlike people who migrated into the Indus Valley around 3500 BCE, significantly influencing the region's culture, society, and religion.
Step-by-step explanation:
The warlike people group that migrated into the Indus Valley were the Aryans. These nomadic Indo-European speakers, who identified themselves as Aryans, began migrating into the region from the Eurasian Steppe north of the Black and Caspian Seas around 3500 BCE. They were a Sanskrit-speaking group of nomadic pastoralists who raised cattle and horses, spreading into Europe, Anatolia, Iran, and then southward into Pakistan and India over time.
The Aryans' migration significantly impacted the local societies, contributing to the emergence of new cultures and social structures, including the establishment of the Hindu caste system. The religious texts known as the Vedas, which were hymns brought by the Aryans to India, became fundamental to the development of Hinduism.