#like refine it away from 'and then they brainwashed the entire continent'

[bestworstcase]

Hey, me and my friend are developing our own Tangled History Lore the involves the Saporians, and in our instance, Demanitus helps Corona take over Saporia by stealing Zhan Tiri’s created memory wand and wiping their memories of the invasion except for the Saporians who helped Corona.

Now, Saporians have grown up with no history of the past other than small events, barely care about their heritage, and are still somewhat against Corona.

So what would happen to the rest of the Seven Kingdoms, who may have been previously allied with Saporia, if they found out Corona and Saporian treasonists took over and wiped their memories

so if i'm following, corona rapunzel's returned the entire nation of saporia and all of saporia's allies ~two thousand years ago when demanitus and zhan tiri were still kicking around and this massive magical conspiracy then went undiscovered for however long—i assume until around the time of the series itself?

which. hm

backtracking a little from your actual question i think it would be worth taking into consideration the limitations of the wand of oblivium—bc in rapunzel's return it's shown that the wand is powerful but can't really be used on a wide scale: the saporians managed to wipe the memories of the coronan king and queen, and being generous perhaps a handful of other aristocrats and important courtiers whom we just don't see on screen bc they're not necessary to the story, and then just relied on the coronan culture of absolute obedience to the king to control the rest of the populace while waiting for varian to figure out a potion that could... either directly reproduce the effect of the wand on a dramatically larger scale or else somehow serve as a conduit for disseminating the wand's magic to many people at once. (personally i think the latter solution was more likely what the goal was, i.e., clementine uses the wand to curse batches of varian's potion and then they suffuse the water supply with the potion or start gassing people with it or whatever the method of distribution ended up being and the curse is transmitted through the material of the potion—but that's a tangent)

so

the question is how did demanitus and his coronan conspirators get around the problem of the wand needing to—as rapunzel's return implies—individually curse every single person whose memories the caster wants to alter? conquest by brainwashing is arduous to the point of impossibility if you're trying to do it one person at a time, esp. when it's possible for cursed people to fight off the magical amnesia with support from loved ones whose memories are intact. and then add to that it being a wand he stole from zhan tiri and his own self-admitted unfamiliarity with magic—this is the man who shoved his soul into a monkey with a spell he knew he barely understood after all—and theres the additional problem of did the coronans even know what they were doing the way a real witch like clementine or zhan tiri would?

and then all magical considerations aside you have the further complication that massive conspiracies are difficult to pull off simply because they require a lot of people to be in the know to make things happen, and you start running into the two-can-keep-a-secret-if-one-is-dead principle. stuff gets out

ANYWAY

this is cynical but assuming there is indeed a two thousand year gap between the memory wiping and then modern day corona, in line with the canonical timeline of tts—which i recognize is not necessarily a reliable assumption with an au but you didn't specify—i honestly dont think a lot would necessarily change if the brainwashing was retroactively discovered somehow. bc by now the hegemony of the seven kingdoms in a world where saporia doesn't exist is well established and... people in power cleave to the status quo. what's going to happen to this sprawling trading alliance if we take corona to task for this enormous violation of human rights that happened literal thousands of years ago? when saporian culture was eradicated so thoroughly that it might as well not ever have existed? who benefits from tearing this system apart now, and who benefits from leaving things as they are and shrugging at past wrongs? (it's so much easier to just say well... that was a long time ago... oh well.)

except for, of course, the saporians themselves, because it was their identity and their home and their culture that was utterly stripped from them—they lost everything, and even the knowledge that they'd lost anything at all was stolen from them too, like, it's hard to fathom a scenario where this information comes out and doesn't lead directly to outrage and unrest from whatever saporian communities are still left—how else can one even respond to something like that?

and from there i mean. it depends on where you want to take the story and how you want to handle it, like, theres a lot of variables beyond "corona did this horrific thing x centuries ago and now we know about it" that could or would shape the direction of events subsequent to the conspiracy being broken up to—like assuming all other things being equal how do zhan tiri and cassandra and the moonstone fit into this, with zhan tiri being (i assume) a saporian sorceress whose work was stolen and then used to eradicate her home? how does varian's partnership with the saporian separatists go when theres this underlying element of them just doing to corona what was done to their ancestors in a desperate bid to maybe scrape back together some semblance of a cultural identity for themselves? how does rapunzel—who has herself run afoul of saporian memory magic, albeit accidentally—feel when she learns this about her nation's history and what does she do about it? etc etc etc and then all these individual character decisions have ripple effects that shape the broader societal and political responses there's not a one size fits all answer, here. it's dependent on the specific shape and structure of the story itself