"However, archaeological evidence of the diffusion of material culture from Western Eurasia into India has been limited."

Exactly! There is no archaeological evidence to point that there was any Aryan "invasion". Besides, there have always been CAUCASOIDS in India. The oldest Caucasoid female lineage(mtDNA marker U2i) in India is dated 50,000 years.

Source: Human Genetics (2001) 109(3):339–350

Our data also support the earlier finding that some of the western Eurasian haplogroups found in India may have been present in India prior to the entry of Aryan speakers.

Even Indus(Harappan) Civilisation had Indo-Aryan custom of fire altars and others.

Source: Allchin, F. (1995). The Archeology of Early Historic South Asia: The Emergence of Cities and States. London: Cambridge University Press.

A rather different picture is presented by the evidence found in the Indus urban settlements. [...] At Kalibangan the curious ritual hearths reported in domestic, public and civic situations are suggestive of a practice ancestral to the Indo-Aryan fire sacrifices, and it is an indication of the presence of Indo-Aryan speakers already during the Harappan urban phase.

Remember that Harappan Urban Phase is around 2500BC(the height of Harappa), 1,000 years BEFORE the so-called "invasion" of Aryans.

Also, the so-called "East Asian" mtDNA marker "M" originated in India and later was carried to East Asia and East Africa by Indians.

Source: Human Genetics (2001) 109(3):339–350

...our past and the present data show that haplogroup M is ubiquitous throughout India. Further, there is no significant cline of the haplogroup M frequency from southern India to northern India.