《明史·志·卷五十六》
茶户要办本身的赋税，便私自贩运出边防，番族以私茶价低贱为有利，于是不肯缴纳马匹。
茶户欲办本课，辄私贩出边，番族利私茶之贱，因不肯纳马。
Tea farmers had to pay taxes themselves, so they smuggled tea out of the border guards. The foreign tribes benefited from the low price of smuggled tea, so they refused to pay for horses.