What does Xuanwu Pass mean?

Xuanwu Pass is Xuanwu Gate. According to relevant records, Xuanwu Pass is the north gate of Taiji Palace and Daming Palace in Chang 'an, the capital of Sui and Tang Dynasties. There were two Xuanwu gates in Chang 'an in Sui and Tang Dynasties, one in the north of Daming Palace and the other in the north of Taiji Palace. There were four Xuanwumen coups in Chang 'an in Tang Dynasty. One of them was in Xuanwu Gate of Taiji Palace. Three times in the Xuanwu Gate of Daming Palace.