Which three Chu do you mean?

Three Chu refers to the territory of Chu in the pre-Qin period, which is divided into western Chu, eastern Chu and southern Chu.

South Chu was the earliest formation. In the eyes of Huaxia nation, Chu is located in the land of barbarians. After the expansion, the Chu people occupied the two lakes, southern Henan, southwestern Anhui, Jiangxi and other regions. During the Spring and Autumn Period, because Chu was located in the south of the Central Plains, countries in the Central Plains called it "Southern Chu". Eastern Chu was in the late Spring and Autumn Period. After wuyue's hegemony, the more it won, the more it occupied Jiangsu and Zhejiang. During the Warring States Period, Chu destroyed Yue and occupied wuyue. This new territory is called Dongchu because it is in the east of the old place.

After the decline of Chu, the capital Ying was conquered by the Qin Dynasty and was slaughtered and destroyed. In order to avoid sharp edges, Chu people moved eastward, and the hometown of southern Chu was no longer the center of Chu. Chu entered and destroyed Lu in the north, occupied Xuzhou, Anhui Province and the north of Huaihe River, and immigrated to Huaibei in large numbers. This area is called Xichu because it is located in the west of Dongchu.

Citations related to the division of three Chu:

Historical Records Biography of Huo Zhi takes Pei, Chen, Runan and Nanjun in Huaibei as the western Chu. The East China Sea, Wu and Guangling to the east of Pengcheng are the East Chu, and Hengshan, Jiujiang, Changsha are the South Chu. According to the fact that Nanjun is isolated from Huaibei counties, it should not belong to the Western Chu. Pengcheng, the capital of Xiang Yu, is called the overlord of the western Chu, and Pengcheng belongs to the western Chu. The question in Biography of Huo Zhi is wrong.

"Emperor Ji of Gao Han" quoted Meng Kang as saying that the old name Jiangling (that is, Nanjun) was named Nanchu, and Wuwei was named Dongchu. Pengcheng is a western Chu. Xichu is about north of Huaishui and west of Si and Yishui. South Chu starts from Huai and Han in the north, reaches Jiangnan in the south, crosses Jianghuai in the east and reaches the sea in the east. In the Taiping universe, Ying (Jiangling) is regarded as the western Chu, Pengcheng as the eastern Chu and Guangling as the southern Chu. This is a rising star, which is inconsistent with the original meaning of Qin and Han Dynasties.