In days of antiquity, legend tells that the strange creatures known as the Thunn’ha descended from the moon along with their city of Ib to come to rest on the edge of a great lake in the land of Mnar. There, they lived in peace for many centuries until Men came to colonise Mnar. These Men built their cities throughout the land, and eventually discovered the city of Ib and the nearby deposits of precious metals. Constructing the settlement of Sarnath close to Ib to mine the ores, the Men looked at the Thunn'ha and hated them because of their differences and perceived weaknesses.
This hatred festered for years until finally the Men could stand it no more and sent their warriors to kill the Thunn'ha. In a single day of frenzied slaughter, the poor creatures were wiped out, their city destroyed, and the idol of their god Bokrug stolen by the human High Priest.
Returning to their city the Men made merry and celebrated the victory, but the very next day found their High Priest in his temple, dead of fright. Before he died, however, the Priest had managed to scrawl the symbol for Doom upon the wall.
Over the next millennia, the city of Sarnath prospered, becoming the most powerful and opulent metropolis on Earth, and celebrating the anniversary of the scourging of the Thunn'ha each year. Yet every year during these revelries, the people of Sarnath noticed strange ripples across the lake on the edge of town.
During the festivities for the one thousandth anniversary of the destruction of Ib, a strange darkness began to descend from the moon, while simultaneously a green fog rose up to meet it from the surface of the lake. The Men of Sarnath began to run from their city in droves, looks of mindless terror written across their faces; they had peered into the Great Hall of Sarnath and seen not their lords and nobles, but creatures cast in the image of the Thunn'ha. Whether Bokrug had come and replaced the Men with his own worshipers, or transformed them into Thunn'ha is unknown, but the end result was the same.
Many years later, when other Men plucked up the courage to seek out Sarnath, they found nothing, not the ruins of a razed city, not even the mines sunk deep beneath the ground. All that rested there was an ancient, weed-encrusted statue. These Men brought this statue back to their own city, and began to worship Bokrug out of fear.
- Bokrug made its first and only appearance in The Doom that Came to Sarnath (1919), by H.P. Lovecraft.