《明史·志·卷五十六》
广东出产的盥按例不出其境，商人大都买通守关官吏，越境到广西出售。
广东之盐，例不出境，商人率市守关吏，越市广西。
According to the regulations, Guangxi’s soap should not leave its territory, but merchants mostly bribed the guarding officials, crossed the border to sell to Guangxi.