Up to the 12th century, the period saw the elaboration and extension of the seigneurial economic system (including the attachment of peasants to the land through serfdom); the extension of the feudal system of political rights and obligations between lords and vassals; the so-called "feudal revolution" of the 11th century during which ever smaller lords took control of local lands in many regions; and the appropriation by regional/local seigneurs of various administrative, fiscal and judicial rights for themselves. From the 13th century on, the state slowly regained control of a number of these lost powers. The crises of the 13th and 14th centuries led to the convening of an advisory assembly, the Estates General, and also to an effective end to serfdom.