Korea and China were not always cohesive countries. The rough territory of the modern countries varied quite a bit before Genghis Khan (~1200 AD). Many principalities and city states existed, and powerful Kingdoms rose and fell. Silla (Shilla) had united the Korean peninsula in 668, until 935. They were ascendant during a period when Northern China was relatively weak, roughly around the time of this story.
The “Chin” that they referenced, might just imply the general physical characteristics of the people of that area (racially mongoloid, with eye folds), visually distinct from the Caucasian Persians.
Some people traveled thousands of miles, even in the Old Stone Age. There was a period of development with wide ranging trade ties in the Eastern Mediterranean, which included trade goods from what is now China, which experienced a widespread collapse around 1177 BC.
Koreans share ethnic characteristics with Mongolians (like the “Blue spot” near the base of the spine (also shared by other populations which emigrated from what is modern Mongolia, like Turks and Innuit), as well as some linguistic and cultural traits.
The Steppe horse culture of herdsmen living in round tents, which we associate with Mongolians, historically extended into the common, contiguous environment of the Tibetan highland plains, which basically border the Indus River Valley civilizations (modern Pakistan). That ancient Indus River Valley civilization was historically the Eastern edge of the Persian culture.
During the Sasanian era of this story (which in popular memory, might be “the time before the Arab/Muslim conquest” - the good old days of Persian culture), the Persian Empire extended throughout the Indus River plains, high up into the Himalayas. The Government likely maintained formal diplomatic relations, conducted trade, and sought intelligence from the other side of the mountains.
It did not require many cultural hops to make the journey to Korea. It might take a year on horseback, but it was comparable to a journey from the Eastern to the Western edge of the Persian Empire itself.
What a great read. Thanks to all who shared their knowledge.
Mercier