Okay kiddo, let me explain what Dayuan is.
In the olden days, a long, long time ago, there was a place called Dayuan. It was located in what we now know as Central Asia, in an area called the Tarim Basin. It was a real important place for all sorts of different people, because it was kinda like a gateway between East and West.
People who lived in Dayuan were really good at making things out of silk, and they had lots of other valuable stuff like spices, precious stones, and gold. So, many travelers from all over the world would come to Dayuan to trade and get these cool things.
At the time, there were also some very powerful empires and kingdoms, like the Han Dynasty in China, that wanted to be friends with Dayuan, because they knew it was a very valuable place to trade and do business.
So, to sum it all up, Dayuan was a really important place in Central Asia a long, long time ago, where people made and traded valuable things.