Qin dynasty
Note: King Zhaoxiang of Qin (秦昭襄王) had already been ruling Qin for 51 years when Qin annihilated the Zhou dynasty; however the other six warring states were still independent regimes. Some Chinese historiographers thus used the next year (the 52nd year of King Zhaoxiang of Qin) as the official succession from the Zhou dynasty.
Government of the Han dynasty
Qin Shi Huang, the first ruler of the Qin dynasty, established China's imperial system of government in 221 BC after unifying the Seven Warring States through conquest, bringing to an end the Warring States period. For a time, the rulers of the warring states claimed nominal allegiance to an overlord king of the Zhou dynasty (c. 1050 – 256 BC), yet the Zhou kings' political power and prestige was less than that of later Chinese emperors. The imperial system fell apart after the fall of Qin in 206 BC. However, following Han's victory over Chu, the King of Han reestablished the imperial system and is known posthumously as Emperor Gaozu (r. 202–195 BC).