Aoris

Aoris was a planet where the past and the future were engaged in a complex temporal war.

While travelling through the Time Vortex, the TARDIS accidentally collided with a Time Tank which had come from the planet Aoris. Arriving on the planet, the Fourth Doctor discovered that soldiers from the planet's future were going back thousands of years to steal vital resources from their "negligent" ancestors while the past soldiers planted bombs on timed circuits to attack their descendants. Naturally concerned about the temporal implications of this struggle, the Doctor was eventually able to help the leaders of both sides realise the dangers of this approach, arranging matters so that the inhabitants of the future timeline could travel forward another thousand years while a select few remained in their present to oversee the start of the planet's reconstruction and allow it to repair itself in the absence of its population. (AUDIO: The Paradox Planet / Legacy of Death)