From the ancient times of the Greeks and Romans, there had always been a series of trading routes that linked China with Europe.
These were known as the Silk Road because the primary luxury good that travelled over these trading routes was silk from China. In those times it was only the Chinese who knew how to make silk. Silk was enormously prized as a luxury good.
The nature of the Silk Road, even though it was a trading network that existed for thousands of years, people didn’t start on the Silk Road in Beijing and then walk all the way to Constantinople, or to Venice. They would go from Beijing to maybe two or three or 20 days travel down the road, then would sell their things there to someone there. The person there would then take them and move them a little further west, and so on.
And so very few people travelled from one end to the other, even though the connection was a fairly stable one over time.