The regimiento, cabildo de regidores or concejo cerrado ("closed council") was a system of local government established from the 14h century onwards in the Crown of Castile.^[1] A feature of the progressive oligarchization of the form of government in the cities, the change from the overruled concejo abierto system entailed a reduction of the government to a relatively small number of regidores.^[2] Urban oligarchies intended to fully capture the nomination of the regidores (appointed by the monarch in the case of realengo) since the beginning.^[2] The bulk of the establishment of the new regime chiefly took place between 1345 and the later years of the reign of Alfonso XI of Castile.^[3]