Who is the first king in China history?

Qin Shi Huang (Chinese: 秦始皇, 259–210 BC) was the founder of the Qin dynasty and the first emperor of a unified China. Rather than maintain the title of "king" (王 wáng) borne by the previous Shang and Zhou rulers, he ruled as the First Emperor (始皇帝) of the Qin dynasty from 221 to 210 BC. His self-invented title "emperor" (皇帝 huángdì) would continue to be borne by Chinese rulers for the next two millennia.