I mean, take USA for example, is it even the same country after each amendment? After a Civil War? Civil Rights Movement? Landmark Court Rullings?
One could argue that Modern America began in 1965, with the passing of the Civil Rights Act. Or in 2001 when the Patriot Act was passed. Or in 2009 with Citizens United Court Ruling. Or in January 2017 when… you know. Or in January 2025.
When did the country really start?
OP using your logic I define a country as a name, a collection of people and a consistent government.
If you are really going to list every amendment and significant court case as the start of a new government than it would be fair to say no government in the world is older than 10 years.