I can speak of Poland which had a discontinuity of 123 years. For most practical purposes Poland 1918 was not Poland 1795. It had none of the military alliances nor administrative obligations, just a new country out of nothing.
The only continuity was in the collective mind of people who identified as Polish and grabbed the opportunity to fight and (re-)establish their own country.
Now if you look at the continuity of ideas, it gets pretty philosophical so we could leave it to philosophers... if it wasn't for the fact that people use the ideas to justify wars. I don't have a confident answer for continuity between "being Polish in 1795" and "being Polish in 1918".
The only continuity was in the collective mind of people who identified as Polish and grabbed the opportunity to fight and (re-)establish their own country.
Now if you look at the continuity of ideas, it gets pretty philosophical so we could leave it to philosophers... if it wasn't for the fact that people use the ideas to justify wars. I don't have a confident answer for continuity between "being Polish in 1795" and "being Polish in 1918".