《明史·志·卷五十六》
又派遣驸马都尉谢达告谕蜀王朱椿说： 国家专营茶，本来是用以换马。
又遣驸马都尉谢达谕蜀王椿曰： 国家榷茶，本资易马。
The horse cavalry general Xie Da was dispatched to inform the Shu king Zhu Chun: "The state specializes in tea, which is used mainly for exchanging horses.