A more thorough explanation:

A right of occupancy is a legal term that refers to the right of a person or group to occupy a piece of land or property. In the context of American Indian tribes, this right is known as Indian title.

Indian title is a right of occupancy that the federal government grants to an American Indian tribe based on the tribe's immemorial possession of the area. Congress does not recognize tribal ownership of the land, only possession. A tribe or nation must actually, exclusively, and continuously use the property to establish that it is the ancestral home. An individual may claim Indian title by showing that the individual or his or her lineal ancestors continuously occupied a parcel of land, as individuals, before the land was closed to settlers.

For example, if a tribe has been living on a piece of land for generations, they may have Indian title to that land. This means that they have the right to occupy and use the land, but they do not own it in the same way that a person might own a house or a car.

Another example might be an individual who can prove that their ancestors lived on a piece of land before it was taken over by settlers. In this case, the individual may have Indian title to that land, which would give them the right to occupy and use it.