"The shift from India to Europe as the preferred Urheimat was formally due to new linguistic insights.. but it was coincidentally also well-tuned to new political concerns. Apart from rising nationalism which explains the scramble among scholars to grab the Urheimat status for their own country, the main factor was European colonialism, then at its apogee. It seemed natural that the continent whose manifest destiny was the domination of the world, had also brought forth its own proto-historic Indo-European culture and language. Conversely, it seemed illogical that a backward country like India, badly in need of the White Man's civilising mission, could have brought forth the superior European culture."
January 1, 1970
https://en.wikiquote.org/wiki/Proto-Indo-European_homeland