As you can likely gather from the title, Angolmois: Record of Mongol Invasion takes place during the Mongolian invasion of Japan in the late 1200s.
Before the invasion of Japan, Mongolia had already developed quite the reputation, having completely burnt much of Central and Eastern Europe to the ground in 1241 and 1242.
So while the apocalypse looms on the horizon for the exiles on Tsushima island, it had already come and gone through Central and Eastern Europe.