The proportions of the vaults and devices found suggest a species with similar physical traits to humans but with no genetic evidence left behind, their appearance—along with their motivations—remain a mystery.
Circa 1600 BCE the Jardaan were already a highly advanced race. By this point they have already created the angara and seeded them throughout Heleus. A comment from Drack while exploring the Remnant derelict on Elaaden seemed to point that the Jardaan did not come from Heleus.
At some point they made the Remnant to safeguard their technological achievements. Structures on Habitat 7 seem to have been made around 2400 to 2500 CE, since the Andromeda Initiative never saw any signs of intelligent life during their initial surveys prior to launching their expedition.
After some kind of conflict centuries prior to the Initiative's arrival in 2800s CE, a weapon was detonated on the Jardaan space station Khi Tasira that caused the Scourge to spread throughout Heleus. After this catastrophic event, the Jardaan sent the hollow sphere world Meridian adrift and then left the Heleus Cluster. They have not yet returned.
On a cultural level, it's suggested that the Jardaan must have been intelligent and capable of large-scale cooperation. Translation of the glyphs at Khi Tasira reveal the Jardaan language closely resembles the angara language.
Nothing so far is certain about the Remnant builders, save that their technology is several orders of magnitude more sophisticated than the Initiative's technology. The Jardaan were able to create an interlinked, cluster-wide planetary network, a feat of engineering beyond the logistics or budget of any known species except perhaps the Protheans and Reapers.
Most archaeotech sighted in Heleus is either their creations or Remnant technology, and are frequently interchanged colloquially. While Remnant technology is noted to be actually less advanced than Prothean tech, the energy requirements alone suggest the Jardaan are a Type II civilization on the Kardashev scale.
Like the Protheans, the Jardaan appear to have reached a level of technological development that utterly eclipses even the most cutting-edge Milky Way devices. Like Prothean artifacts, working Remnant technology is relatively rare and, despite the efforts of various scientists and engineers, very little is known about how it functions. Some of their devices, such as their Vault network, are based on science so advanced that even state-of-the-art AIs cannot even begin to estimate exactly how it functions. Despite its technical sophistication, however, much of the Jardaan's technology appears to have enough similarities to conventional technology that a suitably skilled individual would have little trouble operating it.
Activation of Remnant technology seems to require a synthesis of an organic mind and artificial intelligence.
|Citadel||Asari • Drell • Elcor • Hanar • Human • Keeper • Salarian • Turian • Volus|
|Non-Citadel|| Batarian • Collector • Geth • Krogan • Leviathan • Quarian • Raloi • Reaper |
Virtual Alien • Vorcha • Yahg
|Historical||Prothean • Rachni • Other Historical Races|
|Andromeda||Angara • Jardaan • Kett • Remnant|