Question

why did ashoka did not capture the south India

Answer 1

Ashoka couldn't capture the South India because he had problems occurring with the Sakas or horsemen of North India. South India was also a dry state which can't provide offers to Ashoka. South India was also conquered by Northern India, Saka, Persians, and Greeks which made it a bit more tough for Ashoka to rebel against the South Indians. As far as I'm concerned, Ashoka never ever fought with the South Indians.

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Answer 2

Ashoka during the war of Kalinga killed many people. The site he saw was fearing. The bodies of the dead shoked him. This made Ashoka to move back from his decision to capture South India