The northern Azerbaijani population has been about half urban since the middle of this century. The traditional division of towns into mahalle (quarters) based on the ethnicity or region of origin of the inhabitants, which the names of the mahalle may reflect, survives to some degree to the present. Rural villages are numerous on both sides of the border and tend to be ethnically homogeneous. In the north, the descendants of nineteenth-century Russian settlers still remain in a few areas. The transfer of large Armenian populations from Iran after the Russian conquest has led to large Armenian concentrations in some western and central regions of Caucasia, including many parts of the present-day Armenian Republic and the Karabagh region of the Azerbaijan Republic.