All world plagues and pandemics begin in China.
The biggest plague on mankind begins in Washington, DC.
“All world plagues and pandemics begin in China.”
Maybe there was some genetic variation that predisposed western people to infection by diseases that Mongolians were immune to. The inverse of this seems accepted re American Indians. While many Europians carried DNA from the Steppe migrations , many populations remained remote.
It would be easy enough I guess to compare genetic makeup and geography to recorded incidence. Since Germany and eastern parts of Europe would have had a higher concentration of Mongols, some variation of infections and death might show up assuming control for population density.
I only know enough to wonder about this.