Real Talk though, one of the main issues with explaining Vanguard's lore is that it involves a **** ton of time travel shenanigans(hell it's literally the reason a clan even exists in-lore, cough
Gear Chronicle cough)
Hell one of the main things that happens is a
certain someone gets ****ing deleted(quite literally) from the timeline, thus causing the timeline to split: one where everyone remembers said someone, and another where they don't, but slowly start to remember(this is the "Original" timeline)
Then, through the power of time shenagings, at some point units from both timelines realize something is wrong(particularly in the Original timeline because of the fact without said someone existing there is a literal plothole because said someone was the key to stopping the Star-vader invasion)
Eventually what happens is that units from both timelines meet up(again this isn't really explained that well) and they proceed to *****-slap the Star-Vaders(who by this point have become a regular clan on Cray and are no longer a threat) until they surrender again and proceed to un-delete the person. This causes a time continuum, and bam now people from the past, present, and future now co-mingle ON THE SAME DAMN PLANET
This also includes people being able to talk to their future and past selves(even at the same time) without them going poof like you would expect, which is nice and all.
This attracts the attention of Gear Chronicle, who promptly timey wimey over to Cray, see that it's a hopeless situation to fix, and decide to teach the units on Cray how to control "Stride" (the energy that now is commonplace on Cray because of that time continuum and all the time travel stuff) so that it isn't like everyone is panicking and running around wildly.
And by this point, the series shifts from the original season to G(Generation) and hoo boy the lore here...that's a story for another day..
Annnnd.., I basically just explained everything by accident lmao