This is an informative project that originates from Canada that shows just how many different peoples, nations, and polities used to lie hundreds of years ago on pockets of land that's now largely under the sovereignty of post-colonial megastates.
Their coverage is focused on North America, but there's also entries in South America, Australia, and New Zealand.
This isn't a critique of this project, but a question about the spirit of acknowledgement and reconciliation embodied by this and other projects: Africa bore a crushing toll under colonialism. Its people were kidnapped and sold to slavery, which persisted for hundreds of years. In many cases, they weren't even afforded the dilemma of making unequal treaties. Those who remained in Africa lived under colonial powers until after WWII, then in artificial states inheriting the old colonial borders. Many of these places descended into civil war shortly after their independence, and even today their human development lags behind the rest of the world. Ought we not reconcile that?
Of course, it's not a competition. Injustice done to one ought to stand on its own, without comparison to injustice done to others. But the promise of multinational, classically liberal states like Canada, the United States, Colombia, Australia, is that their people are empowered with the right to thrive regardless of how they found themselves in the country, by blood of conquerors, blood of indigenous peoples, blood of slaves, or as recent immigrants. Belief in this lofty ideal, which doesn't always work in practice when one starts much further behind, is also what sets the stage for the self-reflection, compassion, and the desire for reconciliation.
Other parts of the world aren't so keen on this movement. In Europe, similar desires to recognize past inhabitants of a land are painted as irrendentism, hurt by the association with today's xenophobic nationalists and past conquerors who turned to total war and genocide. In Asia, powerful states regularly engage in the subjugation of ethnic groups to this day, but the powers are too significant to world trade and world peace to condemn and alienate. Preservation of life and limb are surprisingly powerful motivators in suppressing this kind of examination elsewhere. Stability, a reduced level of fear, and a latent sense of guilt among the dominant group in power appear to be the necessary preconditions for this kind of movement to emerge and thrive. This isn't a cynical point, but we ought to collectively acknowledge that.