These Elder Thing scientists, having an imperfect understanding of this dimension's relation to the Mythos (much as we do today), attempted to experiment on Ubbo-Sathlah with the milk of Shub-Niggurath, a substance the scientists had gathered from a certain degenerate subsect of the species that had come to worship the alien goddess. This would produce the ever-spawning monstrosity known as Abhoth (discussed at length elsewhere) which they attempted to lock inside the Earth. Although they managed to keep this beast in check for a time, the rapid spread of Shub-Niggurath's influence weakened the local N-Space and attracted the attention of the Great Old Ones. As Abhoth occasionally strained and escaped its confines, N-Space became more fragile. Finally, the barrier between worlds was thin enough that Cthulhu and his star-spawn traveled across the great cosmic gulf between Xoth (another planet where the populace had foolishly been played by the Great Old Ones) and Earth, coming to roost in Rl'yeh.

The Elder Things at this time came to realize the horror of what they had accidentally brought forth. The sanest members of their leadership embarked upon a campaign to eradicate all traces of Mythos-worshipping cults amongst their number, and any creature bearing the stain of Abhoth was mercilessly destroyed. An enormous and brutal war between the Elder Things and their Yithian allies against Cthulhu and his star-spawn spanned thousands of years. The Great Race and the Elder Things, who combined the scientific knowledge of their two civilizations, managed to find a way to restore N-Space. By doing so, they locked those Great Old Ones who dwelt here into a state of suspended animation (or "deathless sleep", if you will). For Cthulhu and his spawn the capital city of their Earthly empire, Rl'yeh, had become their tomb. Now these beings could only attempt to reach their jailors (and the unwitting other species of Earth) through dreams. Dreams, and the warrior race they had built to combat their foes, the Deep Ones.

During the earliest days of the struggle between the Elder Things and the Xothians, Cthulhu had encountered and manage to trap a portion of the foulness known as Abhoth. His experiments with the corrupted spawn of Ubbo-Sathlah employing hyper-geometric formulae allowed him to isolate and stabilize certain desired mutations. These mutations could, through certain invocations of hypergeometry, be suppressed or activated to hijack the DNA sequence of any creature that had been infected by the Cosmic Cancer. From his experiments the Deep Ones were born. He shared his discoveries with two of his extraplanar allies, Mordiggian and Chaugnar Faugn, who employed the aggressive Abhoth mutations to create the Ghoul virus and the Miri Nigri race, respectively.