Sovereignty is used to describe governments who are self-ruling and independent. A sovereign nation is self-governing and is its own political unit or governmental entity.
We have only to look at the birth of the United States of America to get a picture of sovereignty. Today we speak of the USA as a sovereign nation, but this was not always so. At the beginning of the North American settlement, only colonies existed under British authority. The governments of the colonies were directly connected to their Motherland, with whom they were politically tied.
The self-ruling independence the United States exercises today was initially only a hope and a dream for the American colonists. It was only when the thirteen colonies united together and, figuratively speaking, cut the umbilical cord with Great Britain, that they became their own sovereign nation.
Cutting the umbilical cord is what American revolutionists believed was necessary and was the only way they would become a self-governing people. In declaring their independence they chose the word “dissolve” which comes from Latin, meaning, “to make loose and release from.”
“When, in the course of human events, it becomes necessary for one people to dissolve the political bands which have connected them with another . . . “
During the time of the American Revolutionary War, the thirteen colonies that stood united were surrounded by many tribal nations. There were also other foreign nations that had staked their claims on the continent. The tribal and foreign nations watched as the children of Great Britain dissolved the political band connecting them to their Motherland. The American colonists collectively sought their own unique political status: to be an independent, self-ruling sovereign nation.
Initially, tribal nations wondered what was to become of this feud between Mother England and her children. Many Indians believed this spat between America and Britain was a “family quarrel.”  The Congress of the Revolution was resolved to maintain a continuance of friendship with the Indian tribes, seeking their neutrality during the colonists’ “unhappy dispute with Great Britain.” 
Many of the Indian tribes had already made formal, government-to-government treaties with Great Britain. (Over 100 Indian treaties had been signed with the British government and colonial governments between 1607 – 1776.)  These treaties had been negotiated for various land cessations and for an allegiance of friendship to the Crown.
It was not until the end of the American Revolutionary War in 1783, through a treaty, that Great Britain actually recognized the United States of America as a sovereign nation. A treaty was the formal way self-governing nations made agreements between each other. Through the official signing of the Treaty of Paris, the United States of America was now internationally recognized, for the first time, as part of the sovereign nations at-large.
It is important to recognize that tribal sovereignty has unique attributes that most other sovereigns cannot claim. Early on, the European nations, and later, the United States, acknowledged the existing governments of the indigenous people. The governments of the indigenous people of the North American continent were independent of each other. They were not simply one huge tribal unit. Some tribal governments had alliances with other indigenous tribal nations or other foreign nations. Each tribal government exercised sovereignty over their own people and territories.
“America, separated from Europe by a wide ocean, was inhabited by a distinct people, divided into separate nations, independent of each other and of the rest of the world, having institutions of their own, and governing themselves by their own laws . . . The Indian nations had always been considered as distinct, independent political communities . . .”
Tribal sovereignty is distinctive in two ways:
1) It has existed since time immemorial
2) Tribal sovereignty is inherent, not given
The tribal nations, which predate the United States of America by a long shot, had their own communities and governments for as far back as anyone could remember. A tribe’s sovereignty was never given to them by the federal government. No law created the Indians’ power to govern themselves. The various treaties, agreements and statutes the US government made with, or regarding Indians, have simply recognized the fact that Indian tribes already had such power.
“The very term ‘nation,’ so generally applied to them (Indian tribes), means ‘a people distinct from others.’ The constitution, by declaring treaties already made, as well as those to be made, to be the supreme law of the land, has adopted and sanctioned the previous treaties with the Indian nations, and consequently admits their rank among those powers who are capable of making treaties. The words ‘treaty’ and ‘nation’ are words of our own language, selected in our diplomatic and legislative proceedings, by ourselves, having each a definite and well understood meaning. We have applied them to Indians, as we have applied them to the other nations of the earth. They are applied to all in the same sense.”
 Letter from Philip John Schuyler, Major General of the Continental Army, to Commander-In-Chief George Washington, Aug. 27, 1775, about a meeting with a large body of Indians of the Six Nations. “Being apprehensive that we should request them to take up arms in our cause, they explicitly declared, that, as it was a family quarrel, they would not interfere, but remain neuter, and hoped we would not desire more of them.”
 Resolution of the Continental Congress, June 30, 1775; The following month another Resolution of the Continental Congress, July 12, 1775, stated that securing and preserving the friendship of the Indian nations was of utmost concern to the united colonies and they wanted them to refrain from “taking any part in the present commotions.”
Excerpts used by permission from: "Understanding Jurisdiction on Tribal Lands - A User-friendly PL 280 Resource Guide"