Blue (White) Horses

…It is also called Kenraimon. Because the Aouma no Sechie (White Horse Ceremony) was held in front of this gate, it is also called the Aouma Jin (Blue (White) Horse Camp). There is no equivalent to this gate in Heijo Palace, and the inner sanctum of the Imperial Palace is directly connected to the Daigokuden (Great Hall) without any partition between them. …

*Some of the terminology explanations that refer to the "Blue (White) Horse Formation" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…〈けんらいもん〉ともよむ。白馬節会（あおうまのせちえ）がこの門前で行われたので，青(白)馬陣ともいう。平城宮にはこの門に相当するものはなく，内裏内郭が中隔をへだてずに大極殿に接している。…

※「青（白）馬陣」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報