A short term violent oppression is more effective in suppressing dissents and opposition. As we have witnessed Mongols brutal campaign that subjugated various and numerous of empires and ethnics. For those who dared to fight them, Mongols killed and genocides all of them. When all the males were killed and females enslaved, there were no opposition except a pile of bones.
For a long term imperialism and colonialism, such occupation would only be effective if integration and forceful assimilation are adopted. Either the rulers adopted the local custom and married the local and integrated into the local or the local subjected to integration by forcing them to adopt the religion, culture, and language of invaders. But either ways, the integration and interracial marriage need to happen. Otherwise, we would have the Western imperialism and colonialism that treated the subjects as slaves or subjects of exploitation which no matter how long and sophisticated would breed resentment and hatred that would be remembered for a long time.
Western imperialism only successes in America as natives were mostly killed, genocide, put into the reserves which is pretty a internment camp or died due to diseases and hunger. Exception is those more populated central American natives that got assimilated through brutal suppression. Canada and the US both have had boarding schools that dragged native children out of reserves and forced them to assimilate or brutally killed for any native kids that didn't behave.
Even the Spanish conquistadors could not 100% subjugate the Aztec, Maya and Inca, despite mass disease and violence, and suffered centuries of revolts. So even western imperialism in the Americas, of medieval tech vs. stone age tech, couldn't succeed when relying on pure violence alone.
Nahuatl and Maya are still used in Mexico, and was historically an official language of Spanish Mexico. In fact, it wasn't only Native Americans learning Spanish, the Spanish had to learn Nahuatl and the conquistadors even imposed Nahuatl and Spanish concurrently on conquered tribes that weren't Aztecs.
Quechua is still an official language of Peru and was an official language of Spanish Peru. And the Spanish still learned it and imposed it on other tribes, alongside Spanish itself, as an official 'native' language.
Even in the case of 90% casualties, extreme brutality from Spain and total technological overmatch, conquered Native Americans were still able to survive and keep some of their culture in Latin America.
