Entac was a planet in the Milky Way galaxy which was home to primitive species. Sometime prior to when SG-1 visited Netu, Sokar conquered Entac and took it as his own.
Shortly thereafter, Martouf was tortured by Apophis with the Blood of Sokar on Netu and revealed—falsely—that Entac was the location of the central Tok'ra base. Apophis tried to use this information to gain a position of power under Sokar, but Sokar revealed to him that he had recently conquered the planet and found no Tok'ra there. (SG1: "The Devil You Know")