As the Ming dynasty required Japan (that is, the bakufu [Japanese feudal government headed by a shogun]) to crack down on the wako, the bakufu continued to trade using official ships and prohibited private foreign trade in the hope that they could exercise total control over existing profits from private foreign trade; thus, trade using Kangofu was implemented.
明は日本(幕府)に倭寇の取り締まりを求め、幕府も公船で貿易を行ない、私貿易を禁止すれば、既存の民間貿易の利得を幕府側で一手に引き受けることが可能になるという目論見から、勘合符を用いる貿易が推し進められることとなった。