The use of the writings of Karl Marx and Friedrich Engels, which depict a materialist model of social change, to understand past societies. Change within a society is seen as the result of contradictions arising between the forces of production (technology) and the relations of production (social organization). Such contradictions are seen to emerge as a struggle between distinct social classes. Marxist archaeology is built on the notion that an understanding of who has power and how that power is exercised is a vital element in explaining social change.