Vogan War

The Vogan War was a conflict between the Vogans and a group of Cybermen known as the CyberNomads. It took place sometime in the 2150s. (PROSE: Killing Ground)

Origin
According to the ArcHivist Hegelia, the CyberNomads were a Cyber-subspecies that had branched off from the early CyberFaction based on Planet 14, who themselves branched off from the CyberMondasians of the planet Mondas. Hegelia suggested that the CyberNomads had spent roughly two hundred years, from around 1990 to 2190, proliferating throughout the galaxy of Mutter's Spiral. (PROSE: Killing Ground, AUDIO: The Early Cybermen)

The War
At some point, the CyberNomads entered what Jolarr described as a "vicious and protracted war" with Voga, the famed planet of gold and home planet of the Vogan. Ultimately, the Cybermen were defeated by the Vogans and presumed to be extinct by the year 2191. (PROSE: Killing Ground, AUDIO: The Early Cybermen)

As recalled by the Fourth Doctor, the Cybermen waged a failed attack on Voga, either "at "the end" of the Cyber-War (TV: Revenge of the Cybermen) or "after the end" of the Cyber-War. (PROSE: The Revenge of the Cybermen) Most of their ships vanishing after the attack, (PROSE: The Revenge of the Cybermen) the Cybermen disappeared with humanity believing them to have died out. (TV: Revenge of the Cybermen)

Aftermath
Towards the end of the 25th century, (PROSE: Killing Ground, AUDIO: The Early Cybermen) three centuries after the Vogan War, a small, isolated group of CyberNomads, led by a Cyber-Leader and based aboard a single Cyber-ship, reappeared and tried to exact revenge upon the Vogans. Their attempt to destroy Voga, now in orbit around Jupiter, was defeated and they were destroyed with their ship due to the intervention of the Fourth Doctor, Sarah Jane Smith, and Harry Sullivan. (TV: Revenge of the Cybermen)

Hegelia hypothesised that another group of CyberNomads might have came across the planet Telos, reopened the Cyber-tombs of the CyberTelosians and helped to forge the new race of Cybermen, the Neomorphs, which proliferated during the 26th century. (PROSE: Killing Ground, AUDIO: The Early Cybermen)