Alteran Home Galaxy

The Alteran Home Galaxy or Ori Home Galaxy is where the Alterans (the Ancients and the Ori) originated. However, after the Ori became a threat to them, the Ancients decided to abandon this galaxy in order to avoid war with their increasingly fanatical rival group, where they later settled on Earth, which they called Terra, in a galaxy which they named Avalon. The Ancients decided to leave their galaxy behind, to migrate to the Milky Way, which is very far from the Alteran Home Galaxy.

Location
Its exact location in the universe is unknown, but it appears to be very far from the Milky Way, since it would take about a year for Ori motherships to get from that galaxy to the Milky Way on hyperspace travel. The Ancients picked the Milky Way because of its distance away from the galaxy, so the Ori wouldn't easily find them.

Pre-Tau'ri discovery
This galaxy was the birthplace of the Ancients and the Ori, which were known together as the Alterans. However, for a long time, the two factions were over a dispute, as the Ancients believed in science and technology, and the Ori believed in religion. The dispute once become so great that the Ancients were forced to flee after the Ori attempted to destroy them. After the Ancients left, the Ori became the dominant race of the galaxy, and later ascended, where the Ori worked out that if people came to believe in the Ori, then they'd gain their power, with the intention of defeating the Ancients. Some of the humans from the galaxy formed a group called the Anti-Ori underground to expose the Ori as false gods.

Post-Tau'ri discovery
Daniel Jackson and Vala Mal Doran were the first humans from the Milky Way to discover the galaxy via Intergalactic communication device and their accompanying stones, believing that the Ancients actually went home rather than died or ascended. However, their efforts led the Ori to discover the Milky Way, and with their power sent Priors to our own galaxy to increase the number of believers to gain much more power to guarantee the Ancients' defeat. Just before Jackson and Vala burned to death for their "heresy", they returned to the Milky Way after the communication device was destroyed by the unstable vortex of a Stargate.

Over the next few months, the Ori recruited an army to build space ships to carry out a crusade to wipe out all the unbelievers in the Milky Way and show their true power to believers in the Ori. They attempted to construct a Supergate so the ships could carry out the crusade. Fortunately it was destroyed, but Vala travelled to the galaxy to the planet Ver Isca, where she spent her time there joining the underground and marrying Tomin, who became a soldier. She eventually returned to the Milky Way.

In 2007, they sent the Sangraal through the Supergate to kill the Ori. The plan worked, though Adria ascended and took all the power for herself. SG-1 later travelled to the galaxy by Supergate on the Odyssey to retrieve the Ark of Truth and ended up using it to spread the truth of the Ori to the people of that galaxy. The device was activated, and all the Priors saw the "truth", leaving every human in the galaxy to denounce the Ori.

Races native to the galaxy

 * Alterans
 * Ori
 * Ver Egen
 * Ver Iscans
 * Priors

Known Alteran Home Galaxy planets

 * Celestis
 * Ver Isca