The Age of Rassilon
In order to deal with the problems facing the empire, Rassilon instituted several changes. Rasslion instituted the creation of genetic looms to enable the Gallifreyan race to reproduce. The Great Houses were formed to stabilise society. (NA: Cat's Cradle: Time's Crucible)
Following these early changes, the Time Lords began research into black holes, the first race to do so. (DW: The Satan Pit) One of Rassilon's early attempts to create a black hole accidentally punched a hole through space into the Yssgaroth's Universe. The Yssgaroth escaped and caused mass destruction. The Time Lords, led by Kopyion Liall a Mahajetsu, tried to stop them, leading to the thousand year Eternal War. They were eventually able to push the Yssgaroth back into their own universe, while Kopyion Liall a Mahajetsu guarded the final opening. (NA: The Pit)
Later, Omega utilised two stellar manipulators, the so-called 'hands' of Omega, to detonate a star (DW: Remembrance of the Daleks, PDA: The Infinity Doctors) known as Qqaba and create a black hole from which the Time Lords drew the power they would require for time travel. Omega was himself cast through the black hole into an anti-matter universe and was presumed dead. (DW: The Three Doctors, DWM: Star Death, BFA: Omega) Rassilon eventually retrieved the Eye of Harmony and stored it in a vault beneath the Time Lord capitol as a source of power. (PDA: The Infinity Doctors)
The Eye of Harmony may have been a different black hole than the one created by Omega.
Ancient Gallifrey. (NA: Lungbarrow)At this point, the Non-interference policy was instituted, after the damage that had been done by the Time Lords to other species. (DW: Underworld, PDA: The Quantum Archangel)
Rassilon's reign also saw the war with the Great Vampires (DW: State of Decay) and the end of the games in the Death Zone, blood sports where combatants from throughout time and space fought for the amusement of onlookers. (DW: The Five Doctors) During the Millennium War 150 million years ago, Rassilon went against the non-interference policy and led the Time Lords against the Mad Mind of Bophemeral. (PDA: The Quantum Archangel)
One legend says that despite his great achievements, the Time Lords, with good reason, rebelled against Rassilon and imprisoned him in the Dark Tower in the Death Zone. (DW: The Five Doctors)