It doesn't, and it does. Many people think that the government of the Cherokee Nation has rights which are inherent from time immemorial. Its doesn't and it does. What this confusion boils down to is a lack of knowledge of the origin of sovereignty and an allowance by the people of improper usage and abuse by a rogue government. The government of a nation is not, in and of itself, sovereign.
Sovereignty is a delegation from the people to the government of the right to govern.
It is permission, either written or understood, that a government has some right to represent the people in matters of state and foreign affairs. This is usually accomplished in one of two ways. First, it can be taken from the people, as in the case of dictatorships and other forms of totalitarian regimes. The second is for a valid delegation from the people to a form of government, usually through an election, which then, by consent, exercises sovereignty. As an example, when the Cherokee Nation existed east of the Mississippi River, intact and unmolested by foreign authority, the powers of sovereignty were exercised at various levels by the people or their designated leadership, priests, chiefs and other headmen.