The parish has historically been of fundamental importance in the administrative and political organization of the Lordship of Bizkaia; there is, moreover, another institution, of a more reduced scope, which in certain rural areas, for instance in Durango, Arratia Valley and environs, has likewise played a basic role: namely, the confraternity, or kofradia.
These confraternities are not devoted to a religious or professional purpose, but they are rather associations of households or families, organized administratively at the neighbourhood level, with a view to provide an adequate response to communal needs. They operate independently of the municipal administration, although some decisions ought to necessarily be made at that higher level. Confraternities are, however, institutions which probably predate the parish.