There is a huge difference and I will tell you the secret. Voices. It is an invasion when enough people are unhappy about it, if enough people are happy about it, then it becomes liberation or unification. The further back we go in history the less it tends to matter how people at the time initial felt- with enough bias or silencing or loud enough propaganda, repeated over even a few generations Can be enough to change the perception of those events and people.
Changing history, changing the present or future often involves hurting people. Almost always does. No matter how seemingly right or “good” a cause someone ends up hurt or feeling hurt. Look at simple concepts of human rights like women are equal people, humans shouldn’t be kept as slaves, your “race” shouldn’t be used to dehumanize you. Look at the global and historical or present day backlash against those ideas.
The moral judgements and such I leave out- from those peoples perspectives even what might be considered universally “good” change causes some measure of harm right? People don’t like to be forced to do things in general, right or wrong. Regardless of the morals of your causes or reasoning, regardless of why benefit you might bring, some people will get hurt. We can generally make this reconcilable by labeling those who get hurt as “bad guys,” which they may or may not be- but we generally don’t feel so bad when the people who are sacrificed or forced to comply backwards their wishes are “bad people” or “backwards”; or we simply don’t care because we are too far removed from the harm.
If you are far from harm but close to benefit you tend to not care, or to be complicit at least. We have no investment generally in lives and people and values and governments from the far past. It’s all “numbers on paper.” If you live through a war you’ll probably have feelings about that. If your country loses or the war changes the world and you are unhappy with those changes you’ll probably having feelings about it. You MIGHT have feelings about what happened long ago IF you can connect it to yourself. So for example, if nation A conquered nation B and your ancestors were from nation B and that conquest has negative effects that reach you today- you’d likely care; but if things turned out fine for a descendant of nation B, they probably don’t care what happened hundreds or thousands of years ago.
Stalin or Mao for example are figures that have shaped the modern world, and people still live today who experienced their negative impacts first hand or live in the direct echoes of their actions. Ancient conquerors like Alexander or the Huns etc. shaped the framework of the modern world but it is much harder to envision a world without those changes let alone see how they may have direct tangible impact to any one person. Many, most, or all the nations and even peoples involved in far off conflicts are gone or effectively gone either in entirety or in practice. The grudge is too far removed unless you “feel” the effects of the deed to the modern day. There is more to it- cultural distances- for example “western” cultures have traditionally given little thought or care to events in certain places or even seen negative events as a good thing.
“Asian” countries have long been marginalized and dehumanized and vilified even by many “western” cultures- The Mongolian armies ripping across Asia are often glorified because of their effectiveness or prowess or some romanticization of what they represent, but Stalin or Hitler ripping across Europe are generally not seen as tales of effective and decisive leadership and prowess so much as evil deeds. There are political and moral and philosophical reasons as well but often a component in who gets hoisted up as a “hero” or at least not s villain depends on issues like race and ethnicity and perceived relatability to the target audience. In places and times where the prevailing outlooks or powers dictate, “barbarian hordes” represent savagery, brute aggression, animal selfishness, the antithesis of civilized peoples and an enemy to humanity. In other times or places the “barbarian” is a counter culture hero.
Changing history, changing the present or future often involves hurting people. Almost always does. No matter how seemingly right or “good” a cause someone ends up hurt or feeling hurt. Look at simple concepts of human rights like women are equal people, humans shouldn’t be kept as slaves, your “race” shouldn’t be used to dehumanize you. Look at the global and historical or present day backlash against those ideas.