Alteran history book
From The Stargate Omnipedia
The only text found among droves of treasure in Avalon beneath Glastonbury Tor, England. It tells of a race called the Alterans who came into the Milky Way galaxy, made their home in Avalon and built a new network of Stargates.
KEY EPISODE
Avalon, Part 2 - Daniel finds an Alteran history book that explains the origin of the Ancients.