Tarkir is the plane in the multiverse which appears in the Khans of Tarkir block. It is unique in that there are two different Tarkir planes which go by the same name, unlike Lowryn/Shadowmoor.

The reason there are two different Tarkir planes are that there are two different timelines, both of which contribute to a very specific storyline. Tarkir is the native plane of the Planeswalkers Sarkhan and Narset, and is the adopted plane of Ugin.

Original Timeline: Khans

On this timeline, Dragons are extinct. Five clans, each embodying three colors of Magic, wage war for control.

  • Mardu: Red/Black/White
  • Jeskai: Blue/White/Red
  • Sultai: Black/Blue/Green
  • Temur: Green/Red/Blue
  • Abzan: White/Green/Black

On this timeline, it should be noted, Narset is one of the Khans, not a Planeswalker.

This is the timeline in Khans of Tarkir.

Alternate Timeline: Dragons

On this timeline, Dragons thrive on Tarkir. Each clan has been supplanted by one of the Dragonlords.

  • Ojutai: White/Blue
  • Silumgar: Blue/Black
  • Kolaghan: Black/Red
  • Atarka: Red/Green
  • Dromoka: Green/White

On this timeline, Narset is a Planeswalker.

This is the timeline in Dragons of Tarkir.

What happened?

To answer the question of why did the timeline of Tarkir diverge, we must go backwards 1,280 years in time, alongside Sarkhan Vol.

Here, we have the final battle between two different dragon Planeswalkers, Nicol Bolas of Dominaria, and Ugin of Tarkir.

On the Khans timeline, Nicol Bolas wins, resulting in the demise of Tarkir's dragons. The Clans still exist at this time, and rise to war against each other, finding no other forces to fight.

On the Dragons timeline, Sarkhan tips the balance in Ugin's favor, resulting in the continued existence of Dragons on Tarkir. They, too, wage war against each other. Humans are merely pawns in the giant chess game the Dragonlords play.

This is covered in the Fate Reforged expansion.

Planes of the Multiverse

Kaladesh‎Kaldheim‎‎Kamigawa‎‎Kephalai‎‎Lorwyn (Shadowmoor)