Generally speaking, there are eight doors, and then two are blocked, so there is a saying of six doors, or look at the article in the post bar, "The city was destroyed in the early Yuan Dynasty, Suzhou had no walls, and five doors were still there." 1352, anti-yuan rebels rose up and Suzhou garrison officials quickly rebuilt the city wall. At that time, a stone forehead was dug under the ruins of Gusu posthouse, and the word "Xumen" was engraved on it, so Xumen was rebuilt, but there was no water gate. In this way, there are six doors: Chang, Xu, Pan, Hong, Lou and Qi. Among them, Nagato changed its name to Jinchang Gate, but people still call it its old name. At the end of the Yuan Dynasty, after Zhang Shicheng entered the DPRK, he built a barbican outside Liumen, which was maintained in the Ming and Qing Dynasties. " Maybe this is the best explanation.