gǔ dài de guān nèi guān wài mào yì xū yào tōng guò guān fāng shè lì de guān kǒu jìn xíng chá yàn.

古代的关内关外贸易需要通过官方设立的关口进行查验。

In ancient times, trade between the region inside and outside the passes had to be inspected at the official checkpoints.