Extended Structure. During the Tang dynasty (618-907) there was a conspicuous transition from a simple family structure to stem and extended structures. The reasons compelling family members from several generations to live together were primarily economic, political, and social. First, the progress of agrarian development required greater cooperation among a large family unit for it to be able to accumulate sufficient capital and labor to achieve maximum economic benefits. Second, the prevalence of Confucianism, in conjunction with Buddhism, emphasized filial piety, especially by Tang times. For example, co-residing families with members from five generations were applauded in society, whereas a married son, living apart from his parents, was condemned. Families of ten or twenty individuals became a common phenomenon in the Tang dynasty and even more popular in Song times (960- 1279). This trend continued without much change during the Yuan (1279-...