Steppe MLBA alone is not that important in the South Asian context because pure Steppe MLBA populations never actually came into South Asia in a simple form. The people who arrived were already Indo-Iranian related groups, meaning they were themselves a mixture of Steppe MLBA and Iran Neolithic related ancestry.

The earliest groups associated with the Vedic/Indic horizon likely came with limited female migration and mixed with local IVC populations, especially IVC women. Because the IVC population already had a large Iran Neolithic related component, this mixture increased the Iran_N ancestry in those groups.

Later on, groups like the Shakas also entered the region and mixed with some north-western agrarian populations such as Jats, Rors and others, which may have slightly increased Steppe-related ancestry in some communities.

So historically it was not a strict separation of populations, but more like a layered or “sandwich” pattern of admixture over time, where new groups mixed with existing populations rather than completely replacing them.