"Khuynh cai ha ma" are words commonly found on stelae erected at sacred locations, particularly Van Mieu and Van Thanh. They indicated that anyone passing by these places must remove hat (nghieng long) and dismount their horse (xuong ngua) to show respect to respectful figures and teachers.
Under Nguyen dynasty, the stone stelae on which "Khuynh cai ha ma" was carved were placed in front of important places such as the Citadel, Phu Van Lau, the tomb of Emperor Gia Long, etc. Under the reign of Nguyen Emperors, anyone riding horse by the Noon Gate must dismount the horse and walk to show their respect to the Emperor. In 1821, Nguyen Emperor placed "Khuynh cai ha ma" stele in front of Phu Van Lau where the list of candidates bestowed the doctorate title is publicized after the proclamation ceremony.
The stone steles were destroyed during war; therefore, they were re-erected in front of Phu Van Lau when the monument was renovated in 2016. Collapsed on April 12th 2022, the stele located on the right was erected again on May 7th, 2022.