There is only only one reason why people is considered as the most important element of a state, and that reason is, the people are the ones who make the state.
This means that without people, the other elements of the state will be useless as there will be no people to live in a territory, there will be no people to exercise sovereignty and lastly, there will be no people to be governed or to govern a state.
However, the other elements of the state are important too. Each element are not called element if any of it can be disregarded. Each element has its space to complete the state.
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Elements of the state
Personal definition of government#LetsStudy