Longest civil war fought over a continuous period

The world's longest period of continuous civil warfare lasted for 254 years from 475 to 221 BC in China and is known as the Warring States Period or Zhanguo shidai. Feudal lords in 7 major state kingdoms sought dominance over each other in numerous, intensive battles. King Ying Zheng of the Qin state was victorious, becoming the first emperor (Qin Shihuang) of a unified China.

This record is based on civil wars, involving members of a single country who fought continuously and for the same reason(s). Other states involved (including minor states): Zhao, Wu, Qi, Yan, Han, Chu, Shu, Lu, Zhou, Song, Zongshan. Qin, also spelt 'Chin' (depending on the spelling system used) is where the western name for China has come from.