tribes, and the patriarchal family was their social organization. Shepherd life led gradually to agriculture. Finding a river valley where the soil was so fertile as to tempt them to remain, and where there were mountains, deserts, or seas to protect them from invasion of hostile tribes, they became tillers of the soil. This meant settled homes, permanent houses, perhaps of brick or stone, and therefore the beginnings of architecture, metal tools, division of labor, individual ownership of land, the breaking up of the patriarchal family into the village community, the beginnings of comibes, and the patri rch l family was their cial organization. epherd life l d gradually to agriculre. Finding a river valley where t il was o fertile as to tempt them o remerce, and finally the development of city life.