Who they were
Yu is known only from much later texts such as the Shangshu and Sima Qian’s Shiji, so everything about him must be treated as tradition rather than established history. Tradition presents him as a sage ruler who received the throne from Shun on merit.
What they did
Where his father Gun had failed by damming the great floods, Yu succeeded by dredging channels that guided the waters to the sea. Tradition says he labored for thirteen years and three times passed the gate of his own home without entering. The succession of his son Qi is traditionally said to have begun hereditary dynastic rule.
Legacy
Yu became the model ruler of Chinese tradition: his taming of the floods made water management a founding virtue of statecraft. A mausoleum honoring him stands at Shaoxing.