At the Mountains of Madness

"With the upheaval of new land in the South Pacific tremendous events began.... Another race--a land race of beings shaped like octopi and probably corresponding to the fabulous pre-human spawn of Cthulhu--soon began filtering down from cosmic infinity and precipitated a monstrous war which for a time drove the Old Ones wholly back to the sea.... Later peace was made, and the new lands were given to the Cthulhu spawn whilst the Old Ones held the sea and the older lands.... The Antarctic remained the centre of the Old Ones' civilisation, and all the discoverable cities built there by the Cthulhu spawn were blotted out. Then suddenly the lands of the Pacific sank again, taking with them the frightful stone city of R'lyeh and all the cosmic octopi, so that the Old Ones were once again supreme on the planet..."

(HPL, 1931)