This is from my history, glass and crystal makers from France went all over the world. I created a free space page to house a chronicle written in the 1700s by my 4x Great Grandfather. He lists a lot of locations he worked before becoming a master glass maker and settling in Eastern France.
An international organization made up of descendants of glass and crystal makers called GenVerrE has been trying to trace the routes of the glassmakers. We have seen many come from Altaire and Murano into Austria, what is now called Germany, and into Easter France. Then we see the French glass and crystal makers going into Germany, Sweden, Belgium, England, Scandinavia, Russia, Czechoslovakia, and later Canada and even as early as Colonial America in the US. So if one industry did this I could see where others might do the same.
What did your ancestors do? If any made glass you have your answer. If something else I would look into the trade and migration patterns of that industry.
Another thing to look at is military service.
Hope this helps!