cash exchanges on the Silk Road?

Bob, there were money houses. They cashed their cheques at the money houses. When they went abroad, they used silk and other products to exchange food and other necessities. This is what I got from some theses. I think cash exchanges did exist. It is reported that many ancient foreign currencies have been found in China. The ancient Chinese must have exchanged their money for foreign currencies when they traded on the silk road, I think. That's why these foreign currencies were found in China.