“It is well known that ancient Rome looked upon the ancestors of the present-day Germans and French in the same way as the representatives of the "superior race" now look upon the Slav races. It is well known that ancient Rome treated them as an "inferior race," as "barbarians," destined to live in eternal subordination to the "superior race," to "great Rome", and, between ourselves be it said, ancient Rome had some grounds for this, which cannot be said of the representatives of the "superior race" of today.”

Report to the Seventeenth Party Congress on the Work of the Central Committee of the C.P.S.U. (B.) https://www.marxists.org/reference/archive/stalin/works/1934/01/26.htm (January 26, 1934)
Stalin's speeches, writings and authorised interviews
Context: Still others think that war should be organised by a "superior race," say, the German "race," against an "inferior race," primarily against the Slavs; that only such a war can provide a way out of the situation, for it is the mission of the "superior race" to render the "inferior race" fruitful and to rule over it. Let us assume that this queer theory, which is as far removed from science as the sky from the earth, let us assume that this queer theory is put into practice. What may be the result of that? It is well known that ancient Rome looked upon the ancestors of the present-day Germans and French in the same way as the representatives of the "superior race" now look upon the Slav races. It is well known that ancient Rome treated them as an "inferior race," as "barbarians," destined to live in eternal subordination to the "superior race," to "great Rome", and, between ourselves be it said, ancient Rome had some grounds for this, which cannot be said of the representatives of the "superior race" of today. (Thunderous applause.) But what was the upshot of this? The upshot was that the non-Romans, i. e., all the "barbarians," united against the common enemy and brought Rome down with a crash. The question arises: What guarantee is there that the claims of the representatives of the "superior race" of today will not lead to the same lamentable results? What guarantee is there that the fascist literary politicians in Berlin will be more fortunate than the old and experienced conquerors in Rome? Would it not be more correct to assume that the opposite will be the case?