On this day 621 years ago, on December 23, 1404 (November 21, 1404 lunar calendar), Emperor Chengzu of Ming named "Tianjin". On December 23, 1404, Emperor Chengzu of Ming named "Tianjin", which means Tianzi Ferry, and built the city and set up Tianjin Wei. Tianjin is located in the North China Plain, bordering the Bohai Sea in the east and Yanshan Mountain in the north, with Haihe River winding through the city. The Jin Dynasty established a military town "Zhigu Village" at the mouth of the Sancha River. The name "Zhigu" began to appear in historical records and was the earliest name of Tianjin. In the Qing Dynasty, Tianjin was promoted to Wei as a prefecture and Zhou as a prefecture, but the word "Tianjin" remains until today. Emperor Chengzu of Ming also ordered the establishment of Tianjin Guards, Tianjin Left Guards, and Tianjin Right Guards, collectively referred to as "Three Guards" at that time. "Guards" were the military establishment of the Ming Dynasty, led by commanders and envoys, and went straight to the governor's mansion of the later army. Each guard had a total of 5,600 soldiers, and the Tianjin Sanwei soldiers had a quota of 16,800 to guard the capital that would be established and maintain local security. The historical origin of the name of Tianjin varies, and there are roughly the following: Poetry: The word "Tianjin" first appeared in the poems of Qu Yuan, a poet of the State of Chu in the Warring States Period. In "Li Sao", he wrote the high-spirited verse "The dynasty began in Tianjin Xi". Xingguan Zhi said: The name of "Tianjin" comes from the name of Xingguan "Tianjin Xing", and the "Sui Shu ¡¤ Astronomical Records" recorded when recording "Jiukan Donglixing": "The tail is also Jiuzi Ji, also known as Tianjin". The name of the river said: "Tianjin" comes from the name of the river "Tianjin River", and the "Golden History ¡¤ River Canal Records" recorded: "Tongji River created a member of the river patrol officer, who was the same division as the Tianjin River, overseeing the banks of the Caohe Gate, and the above name was Tianjin River patrol officer Li Du Water Supervision". The saying of giving the name: "Tianjin" is the most widely circulated, the most complete historical data, and the clearest recorded saying is derived from the emperor's name. Tianjin means "Tianzi Jin Du", which is the success of Emperor Zhu Di of the Ming Dynasty in seizing the throne. It began when crossing the Guhe River. On November 21, the second year of Yongle (December 23, 1404 AD), the oracle was passed down to "build a city and dredge a pond, and give the name Tianjin". The Ming Dynasty scholar Li Dongyang's "Inscription on the Reconstruction of Sanguan Temple", in which the inscription is: "Tianjin symbolizes the place where the emperor crossed by chariots and horses".