In a parallel universe affected by the Kelvin timeline, New Earth was a colony established by Humanity after the destruction of Earth by the prochronistic Romulan terrorist Nero. (TOS - Boldly Go comic: "Issue 14")
In the mid-23rd century, Nero destroyed Earth before heading for Vulcan, but was stopped by Spock and Nyota Uhura. James T. Kirk and Leonard McCoy perished in the Battle of Andoria. Starfleet Command was relocated to Vulcan. The crass act of destroying Earth led to war between the Federation and the Romulan Star Empire.
In 2263, the Federation was losing the war when Starfleet officers from multiple different realities appeared on Vulcan. Lieutenant Uhura told Captain Jane Tiberia Kirk, Lieutenant-Unit NU-1701 and Doctor McCoy about the loss of Earth, the establishment of New Earth, and the current war. (TOS - Boldly Go comic: "Issue 15")