An ancient galaxy-wide war between the Asgard and the Goa'uld began after the Asgard discovered the Goa'uld and their expansionist nature, and become locked in conflict with the Asgard for the first time in 13,860 BC.
Prelude[]
Seeing the Goa'uld for what they were, the Asgard immediately declared themselves enemies of the System Lord collective and the Goa'uld responded in kind. Relishing the opportunity to flex their muscles, the Goa'uld soon struck against the Asgard but it became apparent that they were more than a match for the stolen technology of the Goa'uld.
History[]
The Goa'uld begrudgingly retreated and, having lost the co-ordinates for their home planet and thus their primary source for hosts, Ra once again called for stockpiles of Naquadah as well as putting an end to the ritual cannibalism which had been a part of Goa'uld society for generations. Nearly four thousand years later, with their resources running low, the System Lords performed a daring attack against both the Asgard and the Furlings which struck a resounding effect. Rather than winning the war, however, this simply caused the two races to fight back even harder and in the years that followed the Asgard dealt the Goa'uld many major setbacks, though strangely did not press the attack. Perhaps if they had known the danger that the Goa'uld would pose to the galaxy in years to come, the Asgard would have pushed harder.
Despite the lack of a head-on attack, many skirmishes and bloody battles raged on for several centuries and, somehow, Ra found himself leaving his Unas host in order to take the body of the Asgard Famrir.
Aftermath[]
However, the Asgard physiology began to reject Ra. Worse, in 9,177 BC, he was injured in a battle with the Asgard. Fleeing his Asgard pursuers, Ra found a lush world in an alien system; Earth. It was there that he found the solution to the lack of hosts in a race of primitives who bowed to his divinity; the Tau'ri. Transferring himself into one of these primitives, Ra became infused with new vigor and life, soon discovering that they provided a near-ideal host for his race. Planting a Stargate which he had brought with him—the original remained undiscovered in the ice of Antarctica—Ra claimed Earth as his own. (RPG: "Living Gods: Stargate System Lords")