Alteran division

"The rift was created, and on that day, the Ori were born."

- The Book of Origin

The Alteran division was a difference of philisophical viewpoints that lead the to the division of the Alterans into the Ancients and the Ori.

The lower planes
Millions of years ago, the Alterans were the first evolution of Humans, on an evolutionary path to Ascension. However, a philisophical division emerged. Those who came to be called the Ori grew more fevrent in their religious belief, while those who came to be known as the Ancients, who still called themselves the Alterans, came to "believe" more in science. Eventually, the Ori became so extreme that the two factions began to oppose each other, culminating in the Ori trying to wipe out the Ancients. To avoid a war, the Ancients left the Alteran Home Galaxy and arrived in the Milky Way.

Even with the distance of millions of light years, the Ori held deep hatred for the Ancients. Daniel Jackson has speculated that the pre-ascended Ori were responsible for the plague that wiped out the Ancients in the Milky Way and caused them to leave for the Pegasus galaxy in Atlantis.

The higher planes
Even when both factions ascended, they continued to oppose each other. The Ori created a new evolution of Humans and passed down a religion called Origin, which placed them as the creators of the universe and promised to ascend those that "followed the path", and destroying all who rejected it. In actuallity, Origin was intended to channel the energy from their followers to the Ori via a complex metaphysical process which essentially drains their followers of power. The Ancients consider this a death of the most meaningless kind, as there is no attempt to achieve enlightenment outside of Ori teachings. Because of this, the Ancients have adopted a strict policy of non-interference with the lower planes, feeling that interference for any reason would make them no better than the Ori. However, the Ancients are believed to have associated demonic and evil conotations with fire, the central icon of Origin.

Even though the Ori's ultimate goal is the destruction of the Ancients, the Ancients will only intervene on the plane of existence they share with the Ori, and even then it is only retaliatory. The Ancients, though opposing the Ori in every way, are unsure if a conflict on that level would result in victory, as well as feeling that conflict would not be the best choice for further enlightenment.

Moros, the last High Councillor of Atlantis, realized the threat the Ori could one day pose, so he descended himself, retaining all of his knowledge and some of his powers, to create a weapon to destroy ascended beings. He entrusted some of his secrets to the Tau'ri monarch Ambrosius Aurelianus, known as King Arthur. To Arthur and his noblemen, the Knights of the Round Table, he became known as Merlin. Moros' weapon came to be known as the Sangraal. However, the Others feared a weapon which could be used against them. They sent Ganos Lal to observe him, destroy the weapon, and, if neccessary, kill him. Ganos became known to the Tau'ri as Morgan Le Fay. She managed to destroy the weapon and kidnap Merlin, causing Arthur and the Knights of the Round Table to go on a quest for the Sangraal. However, Morgan had come to believe that Merlin was right about the threat of the Ori, but knew the weapon was to dangerous to preserve. Morgan then placed Merlin in a stasis pod, hoping to preserve him for when the time came to destroy the Ori.

The Crusade into the Milky Way
The conflict reached a new level when Daniel Jackson and Vala Mal Doran alterted the Ori to the presence of Humans in the Milky Way. Nearly a year later, the Ori Army managed to enter the Milky Way, hoping to convert enough humans to build up their power and destroy the Ancients. To insure that they would also be able to circumvent the rules of the higher planes, one of the Ori allowed herself to be reborn in Vala Mal Doran, allowing one of the Ori to lead their armies as the Orici without intervention by the Ancients. However, even a conflict on that level would have been extremely costly, and the Ori seemed unwilling to risk their collective skins. Knowing that SG-1 had learned of the Sangraal, the Orici, known as Adria, lead SG-1 to the planet where she believed the Sangraal was. SG-1 was transported to another planet, and awoke Merlin, who then began working on another Sangraal. However, Merlin's body had aged too much during stasis, so he transferred his memories to Jackson. Jackson, to give SG-1 a chance to escape, and allowed himself to be captured by Adria.

Merlin was able to protect Daniel's mind as Adria tried to convert him, and protect him when he became a Prior of the Ori. Daniel claimed he would complete the Sangraal for the Ori to use against the Ancients, but he really intended to send it to the Alteran Home Galaxy through a Supergate. Allowing himself to be captured by SG-1, he convinced them to help, and ultimately sent the charging Sangraal to through the Supergate. However, the fate of the Ori is currently unknown, as another six Ori battlecruisers travelled through the Supergate to the Milky Way. Eventually, Adria was captured by Ba'al, and taken as a host. SG-1 attempted to remove Ba'al and replace him with a Tok'ra, but Ba'al released a nerve toxin into Adria. Dying, Adria used the time remaining to successfully ascend. if the Ori are truly dead, she may have assumed all the power they once held. However, it also means that Adria can no longer interfere on the lower planes without inciting the Ancients.