There are various theories about where the boundary is between areas using Kanto type soup broth and those using Kansai type soup broth, such as a Maibara City, Shiga Prefecture theory, Sekigahara-cho (a town situated on the boundary between Shiga Prefecture and Gifu Prefecture) theory, an Oi-gawa River (people in the Edo period found difficulty in wading across Oi-gawa River) theory, and so on.
つゆの関東風と関西風との境界線は諸説存在し、滋賀県の米原市説、滋賀県・岐阜県境の関ヶ原町説、大井の渡しによって分断されていた大井川説、、などの意見がある。