The gate was built in 1420, during the 18th year of
Yongle Emperor's reign. The Gate was originally named "
Black Tortoise Gate" (), but when
Qing dynasty's
Kangxi Emperor, whose birth name was Xuanye (), ascended to the throne, the use of the
Chinese character Xuan () became a form of
naming taboo. The gate is the back gate of the palace, and was used by palace workers. Women being sent into the palace for selection as concubines also entered the palace through this gate. The
Xuanwu Gate Incident, while sharing a similar name with this gate's original name, did not take place at this gate. The palace coup happened during the
Tang dynasty, when the capital was in
Chang'an. ==References==