YAO AND SHUN were legendary sage-rulers of antiquity in China. According to traditional Chinese historiography, Tang Yao (Yao of the Tang clan or state; personal name, Fang Xun) or Tang Dao ruled from 2356 to 2256 BCE. A ruler of great virtue, he considered his son Dan Zhu (or, in some versions, his ten sons) unworthy to rule the empire, and thus selected Shun to be his successor, having first given to him his two daughters in marriage. Yu Shun (personal name, Zhong Hua) served Yao first as a minister, then in Yao's old age as regent, finally succeeding him and ruling for fifty years. Shun in turn considered his son Shang Xun (or, in some versions, his nine sons) unworthy to rule and so he selected Yu as his successor. Yu became the founder of the Xia, traditionally considered to be the first hereditary dynasty...