Dendera, designated P3X-251 by the Tau'ri, is a planet in the Milky Way galaxy which has a Stargate. Earth and Abydos were not the only worlds that rose up against Ra during his reign. Another is the swamp world of Dendera, a planet that has no real natural resources but was extremely valuable to the System Lords anyway.
Dendera was once chosen as a second ground for the Goa'uld, selected as swamp land was reminiscent of the original environments where the first Goa'uld evolved. Dendera was ruled by a queen, Marasis, in Ra's name. Dendera did not offer an easy environment for human civilization to develop, as it possessed little arable land. The Denderan population live as nomads, because Denderans are adept at hunting and gathering, but could never achieve the stability that allowed different cultures to explore science and technology. Even after thousands of years free from the yoke of Ra, Denderans still live in roving bands of hunter-gatherers. (RPG: "Living Gods: Stargate System Lords")