Nankaidō (南海道, literally, "southern sea circuit" or "southern sea region") is a Japanese geographical term.
[1] It means both an ancient division of the country and the main road running through it.
The Nankaidō encompassed the pre-Meiji provincial lands of Kii and Awaji, plus the four provinces that made up the island of Shikoku: Awa, Sanuki, Tosa, and Iyo.
[4] The road extended from Nara to the seacoast to the south on the Kii Peninsula of the island of Honshū in Japan and crossing the sea, extended to Yura (nowadays Sumoto) and then Shikoku.
Many historic earthquakes bear the name "Nankai" or "Nankaido", as specific epicenters were known at the time.