Page "Krypton (comics)" Paragraph 44

The Green Lanterns have dubbed Krypton's sector of space 2813 ( Earth's being 2814 ) and was under the protection of Green Lantern Tomar-Re when it was destroyed.

Another element to the previous version of Krypton was that all Kryptonians were unable to leave their planet or they would die instantly.

This was a result of the Eradicator altering the genetic codes of Kryptonians to keep them planet-bound after a group of them left Krypton to explore and colonize other planets.

The Eradicator punished these Kryptonians by altering their genetic codes to be vulnerable to lead, which resulted in the Daxamites.