Tirekverse

The Tirekverse is an alternate reality version of Equestria created by Starlight Glimmer through the use of her Chrono Trigger spell and the Cutie Map.

History
The history of the Tirekverse was presumably identical to that of the main timeline of Equestria up until the day on which the Mane Six were supposed to receive their Cutie Marks. Starlight Glimmer, seeking to prevent this from happening, traveled back in time, but was pursued by and. Twilight had already witnessed several other alternate realities due to Starlight's actions, and thus acted to stop her. She encased Starlight in a magically created crystal, but the escaped and then tripped  during the race in which she was supposed to perform her first Sonic Rainboom.

As a result of this, an alternate timeline was created in which Tirek succeeded in stealing most or all of the Pony Magic in Equestria and began laying waste to the Tirekverse Everfree Forest. Twilight and Spike, after witnessing this altered present, quickly traveled back in time again, negating this timeline from existence.

Behind the scenes
As with several of the alternate timelines shown in The Cutie Re-Mark, virtually nothing is known about how the history of the Tirekverse unfolded differently than that of the main timeline. This timeline presumably involved Tirek emerging victorious during an altered version of the events of Twilight's Kingdom, due to the Mane Six not being formed and thus unable to use Rainbow Power against him.