It is specifically mentioned in chapter 1 of the Communist Manifesto, a large part of which is talking about the past expansion of capitalism through conquering new market and extending that tendency into the future. Here's one mention:

> The conditions of bourgeois society are too narrow to comprise the wealth created by them. And how does the bourgeoisie get over these crises? On the one hand by enforced destruction of a mass of productive forces; on the other, by the conquest of new markets, and by the more thorough exploitation of the old ones.