Taran-Ish was a high priest of the city of Sarnath in the land of Mnar. When Sarnath conquered the city of Ib and exterminated the nonhuman beings that lived there, the warriors brought back to Sarnath a green stone idol of Bokrug, the Great Water Lizard. There it was set up in the high temple as a symbol of conquest over the old gods and a sign of leadership in Mnar. (HPL: "The Doom That Came to Sarnath")
On the night after the idol was enshrined, eldritch lights were seen over the lake, and by morning the idol had mysteriously vanished. The high priest Taran-Ish was found dead, having died from some nameless fear, but before he died he had scrawled upon the altar of chrysolite the Sign of Doom to serve as a prophecy of warning. A thousand years later the prophecy was fulfilled with the complete destruction of Sarnath as a result of the vengeance of Bokrug. (HPL: "The Doom That Came to Sarnath")