The Chu State was relatively slow in agriculture. But it kept a strong army and with it expanded its territory to the banks of the Changjiang River. Chu lay in the central plains of the middle and lower reaches of the Yellow River. It bordered the Qi, Song, Wei and Han States on the north, the Qin and Ba States on the west, Bai'e on the south and a vast sea on the east. Its land was the largest among the Seven Powers.
Chu began to fall in the late Warring States Period. It failed several wars to Qin, Han, Wei and other states after King Chu Huiwang had became the new ruler. Chu later expanded the embankments of Mianshui and Bishui Rivers and linked them to mountain ranges and high lands by building walls. The whole line was the Wall of Chu. It is known from literatures that the wall ran more than 400 kilometers from east to west. It started at present Biyang County of He'nan Province, moved north to Ye'xian County, turned to the west and hiked over Lushan Mountain, went on southwest and passed through northeast Neixiang County and finally arrived at present zhushan County of Hebei Province.
Recent years' archeological activities have uncovered a 100-kilometer wall that intersects from east to west Xunyang County of Shannxi Province. Layers of stones make the wall and in some place passageways are still perceptible. Further investigations have proved that it is the Wall of Chu. It could be built for resisting the powerful Qin State.
