"In January 1849, months before he migrated to London, Karl Marx published an article by Friedrich Engels in Die Neue Rheinische Zeitung announcing that in Central Europe only Germans, Hungarians and Poles counted as bearers of progress. The rest must go. "The chief mission of all other races and peoples, large and small, is to perish in the revolutionary holocaust."
Genocide arose out of Marx's master-theory of history -- feudalism giving place inevitably to capitalism, capitalism to socialism. The lesser races of Europe -- Basques, Serbs, Bretons and others -- being sunk in feudalism, were counter-revolutionary; having failed to develop a bourgeoisie, they would be two steps behind in the historical process. Engels dismissed them as left-overs and ethnic trash (Voelkerabfall), and called for their extinction.
So genocide was born as a doctrine in the German Rhineland in January 1849, in a Europe still reeling from the revolutions of 1848. It was to become the beacon light of socialism, proudly held and proudly proclaimed."
Found at Dissecting the Left