In light of the economic influences in Kyoto and Osaka, the Edo shogunate, in the name of the regulations for unifying kyo-masu unit, determined to designate the existing kyo-masu as official and to divide 66 provinces around the country into the East and West: the East and the West would be in charge of the Edo Masu-za and the Kyo Masu-za, respectively, each having the rights to the exclusive manufacture, sale and screening of kyo-masu, and the law allowed severe punishment for the manufacture and sale of fake masu.
そのため、寛文9年2月18日に江戸幕府は京都・大坂の経済的影響力の観点から、現行の京枡をもって統一した公定枡とすること、全国66国を東西に分割して東側を江戸枡座が西側を京枡座が管掌し、それぞれに京枡の独占的製造・販売権・検定権を与え、偽の枡の製造販売を厳罰に処することとした（「京枡統一令」）。