premise: Qin dynasty dates back to 221 BC.
hypothesis: Qin Shi Huang ( ; 18 February 25910 September 210 ) was the founder of the Qin dynasty and was the first emperor of a unified China . Rather than maintain the title of `` king '' borne by the previous Shang and Zhou rulers , he ruled as the First Emperor of the Qin dynasty from 220 to 210 BC . The Qin dynasty was the first dynasty of Imperial China , lasting from 221 to 206 BC .