It was located in the Soja neighborhood of the city of Ishioka, Ibaraki Prefecture in the northern Kantō region of Japan.

[1] In the Nara period, after the Taika Reform (645 AD) and centralization of the administration of Japan following Chinese models (the Ritsuryō system), the nation was divided into provinces, each with an official capital constructed per a uniform layout and standard, and headed by an appointed kokushi, who replaced the older Kuni no miyatsuko.

[3] This system collapsed with the growth of feudalism in the late Heian period, and the locations of many of the provincial capitals is now lost.

This area has a dense concentration of kofun tumuli, and is believed to have been the center of the Hitachi kingdom before it was fully incorporated into the Yamato state.

The complex was destroyed during the Tengyō no Ran (Taira no Masakado rebellion) of 939 AD and appears to have been abandoned some time thereafter.