When was the Qin dynasty founded?
Qin dynasty
The Qin dynasty () was the first dynasty of Imperial China, lasting from 221 to 206 BC. Named for its heartland in Qin state (modern Gansu and Shaanxi), the dynasty was founded by Qin Shi Huang, the First Emperor of Qin. The strength of the Qin state was greatly increased by the Legalist reforms of Shang Yang in the fourth century BC, during the Warring States period. In the mid and late third century BC, the Qin state carried out a series of swift conquests, first ending the powerless Zhou dynasty, and eventually conquering the other six of the Seven Warring States. Its 15 years was the shortest major dynasty in Chinese history, consisting of only two emperors, but inaugurated an imperial system that lasted, with interruption and adaptation, until 1912 CE.
Chinese mathematics
Not much is known about Qin dynasty mathematics, or before, due to the burning of books and burying of scholars, circa 213–210 BC. Knowledge of this period can be determined from civil projects and historical evidence. The Qin dynasty created a standard system of weights. Civil projects of the Qin dynasty were significant feats of human engineering. Emperor Qin Shihuang （秦始皇） ordered many men to build large, lifesize statues for the palace tomb along with other temples and shrines, and the shape of the tomb was designed with geometric skills of architecture. It is certain that one of the greatest feats of human history, the Great Wall of China, required many mathematical techniques. All Qin dynasty buildings and grand projects used advanced computation formulas for volume, area and proportion.