The rank wudaifu, a tier nine nobility, was the dividing line between 600-dan officials and high level nobility during the Han dynasty. A look at historical data and related research shows that whenever noble ranks for military merit are spoken of, most discussion centers on the ranks of the wudaifu (or five senior officials). However, this rank was already being conferred during pre-Qin times-in our textus receptus we can see that at least Wei, Qin, and Zhao had a noble (and official) rank called wudaifu. During these pre-Qin times, generals who lead armies to war often held this rank, as it was bestowed on those who made major contributions to the state. In Shang Yang's political reformations in Qin, he established a 17-tiered rank system for military merit (below the first rank was another rank called xiaofu). In this system, wudaifu was listed as tier nine, which places it four ranks above the tier five daifu (which was the starting point for the high level ranks). Therefore, those that attained the rank wudaifu, in addition to the powers and authority given to the high level ranks (as delineated in the Book of Lord Shang), were exempt from corvée and their fief could be up to 600 households in size. When the First Emperor of Qin unified China, the political rights of wudaifu remained the same, with the exception being that now Qin controlled the whole of China as opposed to just a small section in the western borderlands. Historical records and unearthed bamboo strips both show that although their rights and privileges stayed the same, their fiefs were increased in size. Also, in 219 BC, the First Emperor bestowed the rank of wudaifu on the tree than shielded them from the rainstorm, and at the same time he lowered the rank of all those accompanying him and his advisors from the 10(superscript th) level common in the Warring States period to the 9(superscript th) tier of wudaifu. The First Emperor used his authority as emperor to raise the prestigious image of the rank wudaifu, which paved the way for its elevated political status. This took root in the minds of nobility, so that in the beginning of the Han dynasty (when Emperor Hui took the throne), wudaifu was tagged as the beginning rank of high nobility.