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• The Indigenous Aryans theory, also known as the Out of India theory (OIT), is a fringe theory which proposes that the Indo-European languages , or at least the Indo-Aryan languages , originated within the Indian subcontinent, as an alternative to the established migration model which proposes the Pontic steppe as the area of origin of the Indo-European languages.
• The indigenist view sees the Indo-Aryan languages as having a deep history in the Indian subcontinent, and being the carriers of the Indus Valley Civilization  .
• This view proposes an older date than is generally accepted for the Vedic period  , which is generally considered to follow the decline of Harappan culture  .
• It includes arguments against the Indo-Aryan migration theory, and arguments to re-date the Vedas and the presence of the Vedic people in accordance with traditional, Vedic- Puranic datings.
• The idea of "Indigenous Aryans" also implies a migration "Out of India" to Europe and Central Asia. This is contrary to the mainstream scholarly view, saying that the Indo-Aryan languages originated outside India.

for further details, you can refer wikipedia

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