The construction was begun during the warring states period, which was about 2 500 years ago.

长城的建造始于战国时期，大约是2500年以前。

The accomplishment of the Qin was to re-unify China under a single emperor for the first time in 500 years, ending the warring states period.

秦的成就是500年来第一次在一个皇帝的领导下重新统一了中国，结束了战国时代。