"The Doom That Came To Sarnath"

Jason Thompson - mockman.com

by H.P. Lovecraft
originally published The Scot, June 1920

(from Wikipedia) 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.... They 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 all the creatures inhabiting Ib, destroyed the city and took their idol as a trophy, putting it in Sarnath's main temple. 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 empty 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 greenish 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, as the king and the people in the feast had been transformed into the original creatures from Ib.

After this some of the survivors reported seeing the long-dead inhabitants of Ib peering from the windows of the city's 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 ruins, many water lizards, and most disturbingly, the missing idol. Ever since then, Bokrug remained the chief god in the land of Mnar.

Another early, Dunsany-ish tale.  This one clearly points to some ideas HPL will develop later.  It's not a great story, though - more a colorful sketch.