[quote=Gabriel Evings]
True yet not true certainly they have existed before they have existed yet they have not existed forever. They need Sentience in order to exist at all. Should all life ever be wiped out, say by Korn because blood for the blood god, or the tyrranids, as they are a hive mind and the only ones likely to survive would be Tzeench and Nurgle for all things decay and change even space bugs, or Necrons succeed. They would simply stop existing until more sentient life could evolve. So unless life existed before the universe itself then the chaos were not born until the first creature first thought.
[/quote]

Actually, it's quite possible that now that they've been created, while their origins lie in the psychic power of the Ancient Ones, they are beings in and of themselves. At the end of the War in Heaven, the Necron wiped out the Ancient Ones, and the only sentient species remaining was the Eldar. After creating the Eye of Fear and the birth of Slaanesh, they were pretty much wiped out, and yet, even with hardly any sentient life in the universe, the Chaos Gods were not weakened. The Warp, while it is the plane that harbors all sentient thought, exists independantly of sentient life, and is said to have existed even before the Ancient Ones.