The thirteen out of fourty-six dwellings were covered within the Sakurajima Island's stratum, the volcanic ash originated in Sakurajima Island; therefore, it is assumed that they existed during the same time period.
このうち13棟は、桜島起源の火山灰桜島桜島の地層に覆われていることから、同じ時に存在したものと推定できる。