Dialectical materialism or historical materialism was Marx's main scientific contribution: a new theory of history that was supposed to rival what the theory of evolution did to biology, a law of nature for history.
Marx thought that history was driven by material factors, mostly the mode of production and with that knowledge you could explain and even predict historical movement towards a future of a classless society.
historical materialism: (in Marxist theory) the doctrine that all forms of social thought, as art or philosophy, and institutions, as the family or the state, develop as a superstructure founded on an economic base; that they reflect the character of economic relations and are altered or modified as a result of class struggles; that each ruling economic class produces the class that will destroy or replace it; and that dialectical necessity requires the eventual withering away of the state and the establishment of a classless society: the body of theory, in dialectical materialism, dealing with historical process and social causation.
http://www.dictionary.com/browse/historical-materialism
https://en.wikipedia.org/wiki/Historical_materialism
