 The nature of the tribes was mainly geographic, rather than ethnic; inhabitants of Rome were, in theory, assigned to one of the four "urban" tribes, while the territory beyond the city was allocated to the "rural" or "rustic" tribes.Geography was not the sole determining factor in one's "tribus"; at times efforts were made to assign freedmen to the four urban tribes, thus concentrating their votes and limiting their influence on the "comitia tributa".Perhaps for similar reasons, when large numbers of provincials gained the franchise, certain rural tribes were preferred for their enrollment.