Answer :
In general, nation states began to develop in Europe in the 1500s, with the rise in nationalism. Before then, people didn't really think of themselves as belonging to a specific nation.
During the 11th to 14th centuries, the National States arose from the unification of the fiefs in governments exercised by the kings who, allied with the bourgeoisie, promoted the centralization of political power, as well as the unification of weights and measures and the establishment of unified national armies. And, by doing that, they secured more power in the hands of a few families.
