Who brought masses of Armenians to the Southern Caucasus? (documentary evidence)

In October 2020, at the height of the hostilities in Karabakh, French historian and writer Olivier Delorme called from the pages of Le Figaro “stop using the word separatism in relation to Nagorno-Karabakh, Artsakh settled by more than 90% Armenians since antique times”. French intellectual did not make references to any sources or even more to documentary evidence of his words about «90% Armenians from antique times». Qarabag.com tried to verify the claim on the basis of Russian archival materials and Armenian academic research. In order to figure it out, let’s start at the beginning.