Marx's theory of history can be best described as one based on dialectical materialism. This notion of history is one where historical progression is defined by "material existence and by the values and norms associated with the prevailing mode of economic production of the time." Marx's theory is rooted in the idea that there are those in the position of economic power who have accumulated wealth and those who are lacking it.
Historical progression is seen as the defining notions of "economic production" change. The reality of those who own these means of production has always been present. In feudalism, the means of production was defined by land that could be farmed. The landowning aristocracy was the group that possessed the means of production and had power. Serfs lacked it, and thus were relegated to the periphery. As feudalism precedes capitalism, it gave way to not land being defined as the measure of wealth, but industrial capital and profit. For Marx, history changes as the metric that defines "wealth" changes. The presence of a ruling class is what Marx sees as the only constant: "The ideas of the ruling class are in every epoch the ruling ideas, i.e., the class which is the ruling material force of society is at the same time its ruling intellectual force.”
Marx's value might not lie in his post- capitalist forecasting. Marx failed to see that capitalism is highly pliable and can be flexible to meet the needs of the worker, and enable them to accept the reality that capitalism presented. Yet, his strength lies in the social critique he offers. Societies are predicated upon those in the position of power and those who lack it. The dialectic of society is this dynamic. Being able to critically examine it and recognize its presence is where Marx's theory of history finds its strength. He might have been wrong on several points, but his critique in how social notions of the good have evolved with distinct "insider/ outsider" status is where strength in his theory exists.