The husband of the ancient princess was Xu. Xu was the title of son-in-law by the ancient emperors of China. Also known as husband, husband, son-in-law and so on. The word "Ma Xu" only appeared when Emperor Wu of the Han Dynasty established "Ma Xu as a captain". Han Shu said: "A captain in the car is in charge of the royal car, and a captain in Mali is in charge of the horse." Yan Shigu, a famous linguist in the early Tang Dynasty, commented that Xu was a "deputy horse". In other words, a captain in the car was in charge of the emperor's own trip, and a captain in the horse was the person who covered the emperor's trip.
In ancient times, when traffic and communication were very closed, Captain Che Feng and Captain Ma Xu had little power, but they were key positions, and they were often held by people the emperor trusted most. For example, among the four ministers entrusted to orphans by Emperor Wu of the Han Dynasty, Huo Guang and Xu served as captains respectively in the train service and Xu. The first coincidence between Xu and the emperor's son-in-law occurred during the reign of Liu Zhuang, the second emperor of the Eastern Han Dynasty.
"The Book of the Later Han Dynasty" contains: "The emperor's daughter, Chifu, was Princess Guantao for fifteen years, and was a captain and Han Guang." It is said that in 72 AD, Emperor Han Ming married Princess Guantao (the third daughter of Emperor Guangwu of Han Dynasty) to Han Guang, a captain of Xu at that time. However, Xu, the first in history to marry the emperor's daughter as a captain, ended up in a terrible fate. The tenth volume of the Book of the Later Han Dynasty says: "(Korea) just sat with King Huaiyang (Liu) and plotted against him." Xu He's patent to become the son-in-law of the emperor was postponed to the Western Jin Dynasty. Qin Ruowang of Song Dynasty said in Yuan Gui of Bookstore: "As a captain of Ma Xu, I went to visit the princess in Shanxi."