Appearance:

Culture:
The Na'kuhl were an alien race from the 29th century lead by Vosk.  They were vehemently opposed to the Temporal Accord and viewed time travel as an innate right, something to be used by all races for self-improvement, despite the damage that might be done to the timeline.  Because of that they were perceived as the most dangerous faction in the Temporal Cold War by Daniels' group.

They were responsible for the Cold War temporarily igniting.  Daniel's faction very nearly defeated and
captured them, but by using a newly-developed form of stealth time travel they escaped to an alternate Earth of the 1940s. In this reality, with the assassination of Vladimir
Lenin by an unknown faction in the Temporal War, Nazi Germany had been able to concentrate
solely on the Western Front during World War II, allowing Adolf Hitler to conquer Belgium, France,
the United Kingdom, and Washington, DC

Since Vosk's time portal was one-way, he allied with Adolf Hitler and Nazi Germany, promising
to provide them with advanced technological weaponry, but held back from
doing so, not trusting the German forces. In exchange, the Germans provided the Na'kuhl with the
materials to build a temporal conduit in New York so they could return to the future and defeat
Daniels' faction and assume mastery over time.

Upon returning to the future, Vosk's people managed to defeat Daniels' and began a series of drastic
alterations to the timeline. Chaos broke out amongst the temporal powers; with this blatant
violation of the Temporal Accord as an instigation, dozens of agents from all the factions began to try
to wipe out one another's histories. One faction assassinated Vladimir Lenin in 1916, creating the
alternate Earth Vosk had traveled to in the first place (a "chicken or the egg" paradox).

Daniels used the last of his resources to bring himself, Enterprise, and Captain Archer to 1944 in a
last-ditch effort to stop Vosk from building his temporal conduit. The sheer volume of temporal
incursions created turbulence in the timestream that severely injured Daniels; he died in the
Enterprise sickbay after managing to explain the situation to Archer and T'Pol.

The Suliban's benefactor took advantage of the chaos, and seeing that Daniels was sending
Enterprise to 1944, he had Silik infilitrate the ship beforehand; he planned to have Silik steal the
plans for the Na'kuhl temporal conduit so that when Enterprise returned to 2154, he would finally
be able to travel through time. Silik succeeded in acquiring the plans, but he was found out by
Archer and Phlox, and was forced to help in destroying Vosk's conduit. Silik was killed by Nazis in
the operation, but the conduit was successfully destroyed and Vosk died in the blast.
When, in 1944 Jonathan Archer and Silik
destroyed the time conduit, it stopped the Temporal Cold War from ever going hot, wiping out the
alternate timeline, and defeating the Na'kuhl.

As a result, the timeline reset itself: Vosk never wiped out Daniels' faction, and the Cold War never
went hot as a result. Earth's history, and that of the rest of time, was restored to its previous path.
Daniels told Archer that the Cold War was "coming to an end because of what you did. You have
no idea how many lives you've saved." It may be that in witnessing the potential devastation that
would result from a full-fledged Temporal War breaking out, the various factions were inspired to
reach a peaceful accord.

References

     ENT: "Zero Hour"
     ENT: "Storm Front, Part I"
     ENT: "Storm Front, Part II"

Individuals of Note:

Ghrath -  A Na'kuhl officer

Vosk - Fanatical Leader of the Na'Kuhl, a faction in the Temporal Cold War. Originating from the 29th
century, Vosk was strongly oppposed to the Temporal Accord, believing it was his right to use time
travel for the benefit of his race.  Enterprise destroyed his compound, just as Vosk was stepping into the temporal conduit to return to the future.  Vosk was killed when the temporal conduit collapsed on him. (ENT: "Storm
Front, Parts I and Part II")

     Vosk wore the military uniform of a WWII German lieutenant colonel (oberstleutnant).
     Since he wore SS insignia, his rank would be listed as Obersturmbannführer (senior
     storm-unit leader).