The Pnakotic Manuscripts are noteworthy for being the first of Lovecraft's fictional arcane books.
The Pnakotic Manuscripts predate the origin of man. The original manuscripts were in scroll form and were passed down through the ages, eventually falling into the hands of secretive cults. The Great Race of Yith is believed to have produced the first five chapters of the Manuscripts, which, among other things, contain a detailed chronicle of the race's history. However, others attribute them to the Elder Things, because of certain similarities to the Eltdown Shards.
The Pnakotic Manuscripts were kept in the Great Race's library city of Pnakotus (hence the name). They cover a variety of subjects, including descriptions of Chaugnar Faugn and Yibb-Tstll, the location of Xiurhn, Rhan-Tegoth's rituals, and others.
The Pnakotic Manuscripts were originally held by the people of Lomar, who studied them diligently. Later, they were passed to Hyperborea and translated into the language of that land. Here the manuscripts were added to by the Voormi. Another addition is known to have been made in earlier times by a scribe in Zobna.
The Manuscripts survived into historical times, protected by a secretive cult known as the Pnakotic Brotherhood, and are thought to have been translated into a Greek in a version known as the Pnakotica. Rumors say that an English translation was made in the 15th century by an unknown scribe, but the consensus is that they exist only in manuscript form. The original scrolls of the Pnakotic Manuscripts are believed to be lost (nevertheless, a copy may still exist in the Temple of the Elder Ones in Ulthar).