Synopsis
According to the tale, more than 10,000 years ago, a race of shepherd people colonized the banks of the river Ai in a land called Mnar, forming the cities of Thraa, Ilarnek, and Kadatheron (not to be confused with Kadath), which rose to great intellectual and mercantile prowess. Craving more land, a group of these hardy people migrated to the shores of a lonely and vast lake at the heart of Mnar, founding the metropolis of Sarnath.
But the settlers were not alone. At the other side of the lake was the ancient, grey-stone city of Ib, inhabited by a queer race who had descended from the moon. Lovecraft described them as "in hue as green as the lake and the mists that rise above it.... hey had bulging eyes, pouting, flabby lips, and curious ears, and were without voice.
These beings worshipped a strange god known as Bokrug, the Great Water Lizard, although it was more their physical form that caused the people of Sarnath to despise them.
The people of Sarnath killed the creatures inhabiting Ib and took their idol as a trophy. The next night, the idol vanished under peculiar circumstances, and Taran-Ish, the high-priest of Sarnath, was found dead. Before dying, he had scrawled a single sign on the altar: "DOOM".
Ten centuries later, Sarnath was at the zenith of its power and decadence. Nobles from distant cities were invited to the feast in honour of Ib's destruction. That night, however, the revelry was disrupted by strange lights over the lake and heavy mists, and that the tidal marker, the granite pillar Akurion, was mostly submerged. Not too much later, many of the city's inhabitants fled, maddened by fear. Some reported seeing the long-dead inhabitants of Ib peering from the windows of the towers, while others refused to say exactly what they had seen.
Those that returned saw nothing of those unlucky enough to be left behind, only rubble, many water lizards, and, most disturbingly, the missing idol of Bokrug. Ever since, Bokrug has been the chief god of Ilarnek.
Read more about this topic: The Doom That Came To Sarnath