Who is Da Yu / Yu the Great from Dragon Bones: A Novel and what is their importance?

Da Yu (Yu the Great) founded the Xia dynasty in China. He was hired by King Shun to control the floods after his father, Kun, failed at the task. Yu was given a gui as a symbol of his task, and in legend, Yu then created mountains and gorges to guide the river to the sea, thereby stopping the great floods. Yu was also credited with teaching the people of agriculture and animals, and with helping to replace the nomadic society with the feudal system. Proof of Yu the Great is what those in the book seek, and in the end, it is believed that the ruyi of Yu is discovered in a cave protected by Wu and his family. It is, sadly, lost to the sea in the end of the book.