It's more of a set of assumptions about 'Old Europe', of which the Basques and the Sami are the last remaining traces, versus the Indo-European versions. The various Indo-European cultures that were ancestral to modern cultures wrote about these cultures around them or they left linguistic traces in substrates and perhaps in the ways that Indo-European languages evolved and why they evolved in those ways.

It's also the same thing as why Arabs are Indigenous to the Middle East after conquering it in the 600s but the Greeks they replaced weren't in spite of being there for 1,000 years prior to that. The concept does have some semantic wordplay and double standards attached IRL.