Driven by a Nazi-like ideology, the Eurondans were once a prominent occupying force on the planet Euronda. One man, the father of Alar, executed a genocidal plan to wipe out a sub-group of Eurondans they called Breeders. Intent on preserving their genetic purity, the Eurondans built an underground bunker they called Euronda Base and began pumping deadly gases into the atmosphere to exterminate their enemy. Breeders were their enemy, Alar revealed, because they reproduce "with no regard for genetic purity."
But the Breeders survived, and for many decades the war waged on. Breeders gained power over the largest body of water on the planet, which the Eurondans needed to power their deuterium-fueled controlled fusion reactors. When the Eurondans discovered the Stargate within their territory and located the glyphs to the original homeworld, Alar made contact with Earth in the hopes that they would render his people aid. SG-1 was sent to investigate, and eventually learned the truth about their war for themselves.
The Eurondans possess advanced technologies, including medical technology and unmanned aero fighters flown by a direct neural interface with a pilot located safely within the underground compound. SG-1 negotiated for this technology and much more, with Jack O'Neill determined to do whatever was necessary to secure it. But when he learned that Alar and the Eurondans started their war to commit racial genocide, the deal was off.
In a final act, SG-1 commandeered several automated aero fighters via the neural interface and flew them into Euronda Base, decimating the war room and destroying all hope of ever defeating the Breeders.
The Other Side - SG-1 strikes a deal with the Eurondans for their advanced technology, only to realize the partnership has too high a price.