Integration and Indigenous rights

Following the so-far successful model of the European Union, a conference of national representatives was held in Brasília on May 23 (incidentally, the anniversary of the Declaration of the Báb) to officially constitute the Union of South American Nations. The Union joins together the previous trade blocs Mercosur - which consisted of Brazil, Argentina, Paraguay, Uruguay, and Venezuela - and the Andean Community - Colombia, Ecuador, Peru, and Bolivia - each of whose members were already associate members of the other bloc. Guyana and Suriname, which are the only English-speaking and Dutch-speaking countries, respectively, in the new union, are still members of CARICOM, the Caribbean Community - the degree of their participation is apparently still being worked out. Chilean president Michelle Bachelet is the president pro tempore of the Union.
I definitely welcome this latest step towards worldwide political and economic integration. As we've learned from the continuing integration of Europe under the EU, it's still possible for countries that have been enemies for decades or sometimes centuries to overcome their mutual animosity and rivaly and join together to work towards unity and progress. Other such unions have been developing in various parts of the world: the African Union, though at present not at the level of integration represented by the EU, holds promise in ending many of the regional hostilities plaguing Africa; the Arab League has served to bring together the many Arabic-speaking countries; and the Association of South-East Asian Nations has the potential to develop into a regional union in the near future. There have also been proposals for political-economic unions in the Pacific region and in North America, though the latter proposal has not been welcomed in any of the three proposed member states (Mexico, Canada, and the US).
My one concern with the formation of UNASUR (as the Union of South American Nations is abbreviated) is the extent of its commitment towards Indigenous rights. In Bolivia, where Indigenous peoples form 55% of the population, a major movement towards re-indigenization of the national culture and economy has been underway for the past two years; an associated process has also been occurring in Ecuador, where 25% are Indigenous. In Peru, which has a 45% Indigenous population, a similar shift has not yet occurred, perhaps due to the country's more conservative government. Occurring within the newly-formed UNASUR, however, it remains to be seen how these unique events will play out - whether they will receive support from the Union or whether they will be prevented from continuing. It would be a tragedy if the peaceful unification of South America's long-antagonistic countries ended up smothering the political and cultural aspirations of the continent's long-suffering Indigenous peoples.

Who owns Indigenous land?

One of the many, many justifications that has been used by defenders of U.S. Manifest Destiny is that, since certain Indigenous groups conquered and displaced other Indigenous groups, these groups have no legitimate claim to the land that they had taken from the previous inhabitants. In their view, somehow, this is supposed to make permissible the subsequent U.S. conquest and appropriation of Indigenous lands. "Well, the Indians were fighting and conquering each other long before the Europeans got here," the argument goes. It's often left at that, as if it were obvious that that fact justifies what the U.S. devoted a huge amount of its energy towards in the course of the 19th century.
Suppose that the Axis had defeated the Allies in World War II, including the United States. The Germans and the Japanese, triumphant, decide to deport the entire population of the United States onto reserves in the Canadian arctic or in Soviet Siberia, leaving U.S. land open for German and Japanese colonists to settle. Would the fact that wars had taken place in North America prior to World War II, including the U.S. Civil War, somehow make the Axis justified in deporting so many millions of people off their land and appropriating it for their own peoples' use? "Well, they had been fighting each other before we got here." I hope this line of reasoning sounds as ludicrous to you as it does to me. Yet apologists for Manifest Destiny continue to trot it out as if it made perfect sense; in fact, this line of reasoning has been so little challenged that Indigenous groups feel the need to downplay their own cultural differences and the various (scientifically-supported) multi-wave models of their migration into the Americas, just to deny the apologists the ammunition that these facts would bafflingly provide them.
The Hungarian people arrived in central Europe from the plains west of the Urals during the 9th century AD, displacing prior Slavic populations in the region that eventually became Hungary. Does this mean that any nation so willing and able could, with complete justification, invade Hungary, expel all the Hungarians to far-flung reserves, and chalk it up to "the Hungarians themselves took the land from its previous owners"? Ludicrous, right? So why has this ridiculous idea been accepted as a legitimate argument in the discourse on the U.S. treatment of Indigenous peoples?