Book of Sothis

The Book of Sothis is a document known mainly through transmission by George Syncellus (died after 810), purporting to have been written by the historian Manetho (lived in the early 3rd century BCE). Modern scholars are nearly unanimous that the book was in fact written by someone other than Manetho, making it a forgery. Its contents are consequently regarded as being of little value to Egyptology.

While the unknown author is considered to have displayed a thorough knowledge of Manetho, the clearest indication of forgery is the introductory dedication to Ptolemy II Philadelphus, referring to him as Σεβαστω (Sebasto) — i.e. "august" or "Augustus", a Roman title that did not appear until centuries after his death.

Syncellus states that Manetho included information from monuments in "the Siriadic land" (variously conjectured to be Assyria, Arabia or Egypt), that had been engraved before the Deluge, but afterward had been translated and stored in hieroglyphic books in Egyptian temples.