At What Point Does a Country Stop Being a Country?

I'm currently worldbuilding a fictional nation/culture and lately, I've been thinking about the concept of a "country." At what point does a country stop being a country? In this case, I'm talking about a nation in which a kingdom and empire had a war that ended in the kingdom's victory and the empire's defeat, causing mass instability that led to the collapse of the empire and widespread but complete destruction of the empire's infrastructure, institutions, and remnants of empire (military assets, roads, monuments, public services, etc.).<br><br>How much of a country's original infrastructure, institutions, leadership, culture, or history would need to be completely gone before you would stop calling that nation a country? (It may be relevant to note that it's still generally the same piece of land with different regions that share cultural, ethnic, and linguistic similarities.)<br><br>What are your thoughts? Thank you! <br><br><br><br>UPDATE:<br><br>Wow, thank you all for sharing your insights! I was going to mark a couple as post because they were really good, but so were a lot of the other comments, so I just marked a whole bunch haha. Seriously though, thank you all so much. A lot of you made excellent points about countries that have gone through similar historical events. I'm planning on using them to influence how I construct this nation's history. I really do appreciate the help and guidance.