- "It is written on the brick cylinders of Kadatheron that the beings of Ib were in hue as green as the lake and the mists that rise above it; that they had bulging eyes, pouting, flabby lips, and curious ears, and were without voice."
- -H.P. Lovecraft, "The Doom That Came To Sarnath"
The thuum'ha were - or possibly are - natives of the land Mnar, seemingly amphibious humanoids who lived near a giant lake in an ancient stone city named Ib. It was claimed they, and the city, had been there as long as had the lake itself. Their city was destroyed and they themselves routed around ten thousand years ago by the human people of the city Sarnath, who found their existence unacceptable.
From their description they share numerous physical characteristics with Deep Ones and those that have the hybridized Innsmouth look. Ib and Sarnath are not given a specific geographic location in "The Doom That Came to Sarnath" - although they are stated to be as far from the waking lands as they are from the Dreamlands - , so it is difficult to determine whether they are near other known Deep One cities.
The thuum'ha - a name apparently given them by the people of Sarnath, and which means no more than 'the Voiceless' - venerated a statue of the great water lizard Bokrug.
However, it is possible that Ibians are merely the name the Deep Ones are given in the Polaris Era, circa 24,000 B.C.
They seem far more docile than Deep Ones from Earth, in any case, being easily overcome by the human people of Sarnath, who routed them to the point of extermination.