In Shang dynasty China, at the site of Ao, large walls were erected in the 15th century BC that had dimensions of 20 m in width at the base and enclosed an area of some 2100 yd squared. The ancient Chinese capital for the State of Zhao, Handan, founded in 386 BC, also had walls that were 20 m wide at the base; they were 15 m tall, with two separate sides of its rectangular enclosure at a length of 1530 yd.

The cities of the