The following is an account of Vort's history, from their alliance with the Irken Empire to their eventual enslavement, as revealed throughout the span of Invader Zim.
Alliance with the Irken Empire[]
Vortian scientists
The Vortian race was originally in alliance with the Irken Empire, and made many powerful weapons for them, such as the MegaDoomer Combat Stealth Mech, Minimoose and presumably the Frontline BattleMech. They also designed most of the Massive, the flagship of the Irken Empire.
However, the Vortians' alliance with the Irken Empire ended on a sour note when Zim created a hideous blob creature on Vort Research Station 9, which devoured Tallest Miyuki, and later Tallest Spork. Because the blob was produced in a Vortian facility, the incidents were unjustly blamed on the Vortians.
Enslavement[]
Vortian Prisoner 777
Planet Vort, homeworld of the Vortians, was conquered by Invader Larb. The Vortians are now forced to create advanced weaponry for the Irken Empire, helping them take over more planets under duress.
Ever since their enslavement, the Vortians have created powerful devices such as the MegaDoomer, as well as the doomsday technology inside of Minimoose and the Vortian liquid substance used for the Santa Suit. However, the Vortians have shown signs of subtle rebellion by purposely flawing their creations. For example, the Vortian-designed Megadoomer rather humorously cloaked itself but not the user. It is also worth noting is that Vortian Prisoner 777 was very willing to hand over the Massive's schematics to Zim with very little convincing needed, despite the fact that he knew and openly stated that it would infuriate the Irken Armada but knowing how destructive Zim could be, 777 most likely hoped the Irken Defective would destroy the Massive with the information given.
The Resisty[]
The Resisty is a resistance group formed by a Vortian called Lard Nar against the Irken Empire. Many other Irken-enslaved sentients aliens have joined this group, although Lard Nar is the only Vortian. The Resisty planned to destroy the Massive by shooting at the sidepods, the ship's one weakness, but they fail and vow to come back.
The Resisty's ship was destroyed when "Shrinky Self-Destruct" was activated. This caused the ship to shrink to a microscopic size and explode. Apparently, this was one of the last Vortian ships left. This would imply that around Vort's conquering, the rest of their ships were destroyed by the Irkens, most likely to ensure that no Vortian technology would leave the planet and be used against them.