Fall of the Cyber-Empire

The Fall of the Cyber-Empire was the final defeat of the Cyber-Empire at the end of the Cyber-Wars.

History
In the far future, during the Cyber-Wars, the Alliance, including Ko Sharmus, sent the Cyberium back through time and space in order to keep it out of the hands of the Cybermen and defeat them. (TV: Fugitive of the Judoon, The Timeless Children)

At some point after the Cybermen lost the Cyberium, humanity managed to defeat the Cyber-Empire which was "brought down to nothing, finally." (TV: Fugitive of the Judoon) The site of the Empire's greatest defeat was left filled with debris and dormant ships, including an intact Cybercarrier with an army of hundreds of thousands of Cyber-Warriors. (TV: Ascension of the Cybermen)

However, while humanity succeeded in defeating the Cyber-Empire, leaving the Cybermen nearly extinct, humanity was left near extinction as well from the war. (TV: Ascension of the Cybermen)

Aftermath
In the aftermath of the Cyber-Empire's fall, the surviving Cybermen began hunting the surviving humans to extinction. Humanity was left pariahs to other races due to the threat that constantly followed them and many of the survivors fled the galaxy through the Boundary to other parts of the universe for safety. (TV: Ascension of the Cybermen)

One survivor of the Cyber-Wars was Ashad, also known as the Lone Cyberman, who sought out the Cyberium in an effort to restore the fallen Cyber-Empire. In 2020, Captain Jack Harkness passed a warning about Ashad's intentions to the Thirteenth Doctor through Team TARDIS and that if Ashad succeeded, the Cyber-Empire could rise again. However, upon encountering the Lone Cyberman in 1816, the Doctor was forced to allow Ashad to take the Cyberium and depart. (TV: Fugitive of the Judoon, The Haunting of Villa Diodati)

The Doctor and her companions chased Ashad back to the far future where he attempted to restore the Cyber-Empire, aided by the Cyberium and a Cyber-Army located upon a Cybercarrier that had survived the war. Although Ashad nearly succeeded, he was killed by in order to gain the Cyberium for himself. The Doctor, her companions and four human survivors of the war ended Ashad's plan for good by destroying the Cybercarrier and the Cyber-Army that it carried while it was on Gallifrey. During this time, the Doctor sent the three known survivors of the human race from the far future back to Earth in 2020 using a TARDIS, allowing them to start new lives in the 21st century away from the horrors of the aftermath of the Cyber-Wars. (TV: Ascension of the Cybermen, The Timeless Children)