Native tribes are and have always been sovereign entities, that didn't end with European colonization. The degree to which the US government acknowledges this has varied over time, obviously, but as recently as the SCOTUS case on the Indian Child Welfare Act (Haaland v. Brackeen[0,1]), it has at least recognized that sovereignty exists.

[0]https://www.scotusblog.com/case-files/cases/haaland-v-bracke...

[1]https://www.ncsl.org/state-legislatures-news/details/supreme...