If I'm remembering correctly, the evolution of coats more or less corresponds with the evolution of firearms? Historical paintings would be to your advantage here, despite the subjects usually being aristocracy - unfortunately there doesn't seem to be a lot of that from Russia, but Balkan clothing has a significant amount of overlap among the different ethnicities in that era. One thing that would stand out, and help others recognize where your character(s) are from, would be embroidery on the coat/cloak. Usually at the bottom corners or around the edges, but sometimes also on any hoods (which may be their own garment, if it's not a character wearing a scarf, instead).
no subject
If I'm remembering correctly, the evolution of coats more or less corresponds with the evolution of firearms? Historical paintings would be to your advantage here, despite the subjects usually being aristocracy - unfortunately there doesn't seem to be a lot of that from Russia, but Balkan clothing has a significant amount of overlap among the different ethnicities in that era. One thing that would stand out, and help others recognize where your character(s) are from, would be embroidery on the coat/cloak. Usually at the bottom corners or around the edges, but sometimes also on any hoods (which may be their own garment, if it's not a character wearing a scarf, instead).