These were collectively known as the restriction on "letting in guns and letting out women," referring to the severe limitations placed by the bakufu on two things, namely the ability of the wives of daimyo stationed in Edo to return in secret to their own territories, and the influx of guns into the Edo region, the latter of which might render military action against the bakufu feasible (In a children's song, "Toryanse" [Ain't gettin' by!].)
これを「入鉄砲出女」と言うが、江戸在住の大名の妻が密かに領国へ帰国することと、江戸での軍事活動を可能にする江戸方面への鉄砲の流入の2つが、幕府によって厳重に規制されたのである（童謡「通りゃんせ」）。