Oshu Sankan - Ou Sankan

…However, after the construction of the Kakuseki Barrier in September 810 (Kōnin 1) to deal with the retired Emperor Heizei's plan to move the capital to Heizei, the Ousaka Barrier in Omi Province replaced the Awatari Barrier as one of the three Barriers. In addition, the Shirakawa Barrier, Nakoso Barrier, and Nezu Barrier in Mutsu Province, which were established as measures against the Emishi, are also called the Ou-U Sanseki. Barrier [Tateno Kazumi]. …

*Some of the terminology used in reference to the "Oshu Sankan" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…ただし810年(弘仁1)9月平城上皇の平城遷都計画に対処する固関以降は，愛発関にかわり近江国逢坂（おうさか）関が三関の一つとなった。なお，蝦夷対策として陸奥国におかれた白河関，勿来（なこそ）関，念珠（ねず）関を奥羽三関ともいう。関所【館野 和己】。…

※「奥羽三関」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