Sanukuma was the name of the Kamishi ruling caste. According to the Eighth Doctor, they existed as legends in the race memory of many species in their galaxy, having guided their evolution during the early days of the universe.
After billions of years of non-intervention, the Sanukuma, displeased with the life in their galaxy, they sent SporeShips to destroy many of the life-bearing planets. Their final plan, which used the Last Great Time War as a distraction, was a sending a SporeShip into the galactic centre, resetting the life on all of the planets, allowing them to start anew. This plan was stopped by the Eighth Doctor and River Song. (AUDIO: The Rulers of the Universe)