The rise of the modern state idea, where territory defined society rather than society defining territory, started in in the 1600s.

The answer is Europe

The idea of a 'nation-state' is actually a modern idea not more than 400 years old.

The post-Renaissance Europe, saw a rise in opposition to Royal families, wars and poverty.

Among this, grew the idea of a 'home land' and a place which one can call home.

Similar to what the Jews believed to be their home in Israel, the land came to define the people, instead of the people defining the land.

Eventually, this thought gave rise to subsequent countries we see today