No need for the word "tribe" here. They are the Dene. They are the Slave. They are the Cree. we don't say "the German tribe" (of Europe), or the Swiss tribe. This term typically is used to describe a smaller group belonging to a larger group. In this case, the larger group is subconsciously thought of Indians, or even First Nations, or Aboriginals. But the Cree, Slave Dene and any other number of nations are not tribes . They are nations. So, the Cree... The Slave.... The Dene....

I think the comparison you draw with modern Germans or Swiss kind of diminishes your point. It would be more appropriate to compare this to Saxons or something analogous, lest your point seem disingenuous.

The use of tribe, incidentally, is common when describing Saxon tribes, who formed a confederation collectively known as the Saxons. The term tribe is not somehow prejudicial, and it would be a poverty to lose yet another perfectly good word to social hypersensitivity.

Not that your point is invalid, from my limited knowledge of the subject you are correct in pointing out that the Cree, et al are supergroups of tribes and correctly described as nations in the historical sense, and in some limited capacity, in a modern sense.

My point is that you risk undermining your claim if you compare them to a modern, fully sovereign nation, because the context is not apt for comparison, and I think readers lose out if they dismiss your statement based on a poor example.