This is how The Fire Villains Timeline goes in The Cutie Re-Mark Part 1.
[Twilight, Starlight, Spike, Optimus, and Rocka come out of the portal]
Starlight Glimmer: [gasps] What happened here?
Rocka: The place is completely wrecked.
[They see a volcanic like castle in the distance]
Optimus Prime: Come on.
[They head towards it and push the door open]
Applejack: That's easy enough. [sighs] When the Crystal Empire returned, it brought the Fire Villains back with it.
[The flashback shows the Crystal Empire returning and the Fire Villains emerging]
Applejack: [voiceover] And it didn't take long for them to force every one of us to fight back.
[We see ponies charging from either side]
[They ram into each other]
[Fire Lord appears]
Fire Lord: [laughs]
[The Fire Villains surround the area]
[The ponies fight]
Applejack: [voiceover] And even with Princess Celestia leading the charge, it still takes every last pony in Equestria doing their part, working day and night, to keep up the fight.