Oh, this is a topic I've been interested in. Though I'm an amateur at best, hopefully, I can give a comprehensive enough account to qualify for this community.

So in the beginning, Canada was not any different from the rest of the western world. Whether it was in French (Les indiens ou les Amérindiens) or in English, we used the commonly used name given to the indigenous peoples of the Americas. To this day, the federal law governing the relationship between the federal government and the First Nations remains the Indian act of 1876, though amended throughout the years. This all started to change in the latter half of the 20th century, around the 1970s, when decolonization was the hot topic and academia was starting to consider maybe "Indians" was not the most respectful term for the indigenous peoples of Canada. In those days, "First Nations" got proposed, as one term among many.

And it might have remained just one term among many, if not for the fact that Canada was in a bit of a turbulent time back then, and here I make my first small detour. The Quebec separatist movement, which we in Quebec spend much of our school years learning, was beating its drums then. The first independence referendum, in 1980, ended a defeat, with 55% voting no and 45% voting yes. Pierre Elliott Trudeau, the father of our current prime minister, promised Quebec that Canada would repatriate the Canadian constitution, should Quebec vote no.

Here I take a second small detour. Canada was independent since 1931 when the Westminister act was passed, but no Canadian government dared to repatriate the constitution, since no one could agree on how it should be structured. Quebec wanted recognition as a distinct society, Ontario wanted its weight in terms of its population recognised, the rest of Canada didn't want to be dominated by Ontario and Quebec, No one really agreed on what shape the constitution should look like. And so to avoid opening the can of worm, successive Canadian government let the British keep the constitution. But now that they were repatriating the constitution, the debate got on.

And now we return to the First Nations of Canada. Indigenous right wasn't really on anyone's mind back then, what with Quebec and such. But the indigenous people of Canada saw the repatriation of the constitution as both a possible threat against their current rights, which were established with the British crown, and a possible opportunity. They got organising, and in organising, they had to choose a name. A common name to represent all of them. In the end, they formed the "Assembly of First Nations", or "Assemblée des Première Nations" in French. This organisation, which comprised of the leaders and chiefs of pretty much all indigenous of Canada, issued "A Declaration of First Nations" in 1982, and applied pressure throughout the repatriation process, becoming quite well known in Canada in doing so. The term still did not make it into the constitution itself, but they did succeed in including indigenous rights in section 35 of the Constitutional Act. Since then, the Assembly of First Nations has remained one of the primary organisation for the indigenous peoples of Canada, and the term has passed into common use.

And to talk a bit about the term itself. The First Nations avoids the pitfall of "Indians" in that it recognises that the Indigenous peoples are diverse in customs, cultures, and language. It also manages to emphasize that they were the first occupants of these lands. Most importantly though, it is a name that the First Nations have chosen for themselves, and have not been imposed by an outside force.

I have to first apologize for being a political scientist and not a historian.

How the Peoples who inhabited, what is now the territory claimed by the state of Canada, prior to colonization by Europeans, refer to themselves, their communities, and are referred to by first the British Crown and now the Canadian state, is an important site of both contemporary and historical political struggle.

When we are talking about the term “First Nations”, we are predominantly dealing with how the state addresses this collection of Peoples, and how they in turn demand to be addressed. (And, of course, whether indigenous nations can or should have this type of collective relationship with the Canadian state at all).

Very few “First Nations” people today, outside of the context of settler society would identify themselves this way. Instead, they would most likely identify themselves with their national or local communities.

Beginning with the Royal Proclamation of 1763, the way in which first the Crown and then the Canadian state addressed these peoples was “Indian”. This term formed the legal and social basis (for settlers) to define a new category of people and their relationship to the state.

This idea has is culmination in the Indian Act of 1876, and the totalitarian powers it granted the Canadian state to reorder the lives (often violently) of this class of people. While the Indian Act has a long and genocidal history, one point that is important to take away is that it (and through it the Canadian state) defined what it meant to be an Indian. And because one of the purposes of the Act was to facilitate forced assimilation, it defined who was no longer allowed to be recognized as Indian.

This a central tension in indigenous life and politics, described by scholars like Glenn Clouthard and Taiaiake Alfred, as the violence of being recognized by the terms of the colonial-state and the violence of going unrecognized.

This tension can be seen playing itself out in the debate over the 1969 white paper (known as The White Paper for obvious reasons). In 1969, in response to the activism of the 1950s and 60s, the Trudeau government and then Minister for Indian Affairs Jean Chrétien, published their proposals to repeal the Indian Act, and to end Canada’s recognition of ‘Indians’ as a class of people.

The backlash, protest and unrest caused by this proposal ultimately forced the government to back down. Central to this response was the National Indian Brotherhood which was formed in 1970 to lobby the Federal and Provincial governments, and specifically to oppose the White Paper.

The official response to the White Paper by the NIB was written by Harold Cardinal, then the leader of the Indian Association of Alberta. The paper titled Unjust Society, and later known as the “Red Paper” formed the basis for an alternative to the White Paper, usually summarized Citizenship Plus. That is, that in addition to Canadian citizenship there ought to exist an ‘Indian Citizenship’ made real through a renewed treaty process, that sets out to redress the harms of two centuries of genocidal policies.

This would become the central idea behind the NIB, and would continue as the NIB reformed itself as the Assembly of First Nations in 1982. Crucially, the AFN is not a collection of Provincial organizations, but gives direct voting membership to every Band Chief in Canada.

Here is when the idea of being First Nations, as form of pluralistic, collective address, to and from the Canadian state has taken root.

The idea of Citizenship Plus was then taken up by the 1991-96 Royal Commission on Aboriginal Peoples. One of the central recommendations of the RCAP is the idea of the creating a Third Order of Government. That is, that Canadian sovereignty currently shared between the Federal Government and the Provinces should be extended to recognize Aboriginal Peoples as a new partner in Canadian sovereignty and governance through the creation of a new governing structure.

This obviously hasn’t happened, but importantly it is not something that most indigenous people want to happen. Many would insist that their Mohawk nation, for example, is sovereign independent of any recognition by the Canadian state. That they are citizens of a Mohawk nation that Canada wrongfully occupies. That Canada is nothing but a bad neighbour, not political project in which they are a citizen.

I want to end this by emphasizing that the ideas and politics implicit in the idea of “First Nations” as a mode of address are controversial, contested, and outright rejected by many. The lines are never really as clear as we make it in narrative, and language always slips between words and phrases.

It’s also important to state that I’m a Settler, speaking from a Settler’s worldview.

TLDR: The phrase “First Nations” is a form of pluralistic, collective address that implies a certain, historically contingent, political relationship between Canadian indigenous people and the state.