Tango okoku ron (the theory of the Tango Kingdom) (丹後王国論)
Tango okoku ron is a theory in which Teiji KADOWAKI asserted an existence of "Tango Kingdom" in and around Tango region (present Tango City, Kyoto Prefecture) during the Kofun period (tumulus period), which is believed to have been independent and rivaled Yamato sovereignty (the ancient Japan sovereignty) (It is also referred to as "Tanba Kingdom" because Tango Province was divided from Tanba Province later).
According to Teiji KADOWAKI, the peak of "Tango Kingdom" was the mid to late fourth century to the fifth century. He assumes that the kingdom came under control of Yamato sovereignty along with the conquest of Izumo by Yamato in the mid sixth century.
Background
It is believed that an independent power existed in Tango region in ancient times due to a large tumulus center found there (Aminochoshiyama Burial Mound, Shinmeiyama-kofun Tumulus, Ebisuyama-kofun Tumulus, and the like), as well as recent excavations and researches.