I want to track my ancestors' citizenship through time, beginning with my grandmother's grandparents, who were born in Lemberg, Galicia, Austria-Hungary in 1867 and 1871. Presumably, they were Austro-Hungarian at birth and by jus soli. But what happened to their citizenship when AH broke up at WWI? And what did that mean for their children (my grandmother's parents) and other descendants?

This is a new topic for me, and I can't seem to find any historical references to citizenship. Any leads would be greatly appreciated!!! Even if you could just point me in the right direction, I am certainly not averse to reading on my own, lol, I just don't know where to start for this topic.