Among these, Saikaido contained Dazai-fu (the local government office in Kyushu region) which was located in Chikuzen Province and, in addition to protecting national borders and conducting external affairs, served to govern all islands under its jurisdiction according to the koku-gun-ri system (province-district-village system).
このうち西海道には大宰府（だざいふ）が筑前の国に置かれ、国境の防衛や外交事務に当たるとともに、管内諸国島を国、郡、里の三段階で統轄した。