  References to their presence in the court of Qin Shi Huang秦始皇 (259–210 BCE), who ruled Qin from 246 to 221. They remained influential to the early part of the Six Dynasties (to the fourth century CE). Most came from outlying regions, and gained influence for their skills in medicine, astronomical prediction and omen interpretation, all of which were linked to the growth of science in early China. They used magico-medical practices on behalf of the health and vitality of the emperor, but also introduced standardized measurement of time, space, weight, and musical pitch.