Yangguan is a place in China where people used to have to go through a big gate to get into the city. It was a very important place because if people were going in or out of the city, they had to go through this gate.
Nowadays, Yangguan is also famous because of a poem that was written a long, long time ago. The poem talks about how traveling through Yangguan can be really dangerous because it's so far away from other cities and there are lots of dangers like sandstorms and dangerous people.
But even though it's dangerous, the people in the poem still say it's worth it to travel through Yangguan because they believe in the value of exploring new places, meeting new people, and seeing new things.
So even though it's just a place with a gate, Yangguan has become famous for its historical significance and the inspiring message of the poem about the importance of adventure and exploration.