A political unit where the territorial boundaries of a state coincide with the area inhabited by a relatively homogenous nation. This implies a shared culture, history, and language within a defined geographic space controlled by a single government. Japan, with its high degree of cultural homogeneity and centralized political system, serves as a strong example. Iceland, with its shared Norse heritage and common language, also exemplifies this concept.
The concept is significant in understanding political geography because it highlights the ideal, though often unrealized, relationship between a people and their government. It allows for the analysis of political stability, national identity formation, and potential sources of conflict when a perfect alignment is not achieved. Historically, the rise of this model in Europe following the Treaty of Westphalia in 1648 reshaped international relations and established the basis for the modern state system.