Aside from average density, agrarian technology permitted urbanization of population to a greater extent than was possible under horticulture for two reasons. First, settlement sizes grew with agrarian technology because more productive farmers freed more people for urban specialty occupations. Second, land and maritime transportation improvements made it possible to supply great cities of 1,000,000, plus inhabitants such as Rome, Baghdad, and the Chinese capital cities. Rome, for example, could draw grain and other bulk raw materials from Sicily, North Africa, Egypt, and Southern France to sustain large populations, even by modern standards, using maritime transport on the Mediterranean. It is productivity per unit of labor and transport efficiency improvements of agrarian technology that had the widest impact on the more peripheral culture core features of agrarian societies.