A nation is essentially a social and cultural unit, that is, it is defined by the attitudes of people rather than by the provisions of laws or treaties.
Unless a body of individuals think of themselves as a nation, there is no nation.
They need not have a state, a country, a religion, even a language to themselves. They may not belong to one race. Equally, a state may rule several nations, or only part of one. A nation may be devided religiously, a religion nationally. Those who speak a particular language may belong to two or more nations. Races are so impure that it is hardly possible to distinguish them.
The only common bond essential to a nation, by definition, is culture.