The real name of this species is unknown, if indeed they have such a name. They are known to the Xindi as the Guardians , to the Triannon as The makers , and more generically as simply The Sphere Builders.  Existing in a dimension which is completely separate from our own, the Guardians long sought to find a way to colonise our universe. Unfortunately for them the laws of physics in our universe are significantly different from their own, and as a result exposure to our space is rapidly lethal to the Guardians. Approximately a thousand years ago they embarked on an ambitious attempt to 'reconfigure' our space, gradually altering the physical laws so that they could survive here.  To this end they built a series of gigantic spheres which interacted with one another to alter the physical laws. By the mid 22nd century this had created the Delphic Expanse, a vast region filled with dangerous anomalies. 
|Species Name :
||Sphere Builders |
Ultimately the Federation led an alliance which defeated the Guardians at the Battle of Procyon V in the the 26th century. Realising that their colonisation efforts would come to nothing the Guardians sought to alter the timeline to erase the Federation from existence.  They contacted the Xindi in the aftermath of the destruction of their homeworld, guiding the survivors towards resources and lending assistance. The Xindi came to trust the Guardians utterly, even worshipping them. In the mid 22nd century the Guardians informed the Xindi that in the future Humans would become a deadly enemy of the Xindi and would destroy their new homeworld. In response the Xindi embarked on an ambitious project to build a weapon capable of destroying Earth and any other Human worlds. In this manner the Guardians hoped that the Federation would never be founded and so would be unable to oppose them in the future. 
The NX-01 first contacted a Guardian in 2153, when a small pod was discovered within a powerful anomaly in the Expanse. The Guardains had sent a test subject to our universe to test his survivability in the reconfigured space. The starship rescued the man, exposing him to our own space. His body began to disintergrate in response, but before his death he attempted to sabotage the NX-01. His actions gave Captain Archer his first clues as to the origin and purpose of the expanse. 
Archer was able to convince some of the Xindi of the Guardian's true intentions , but the Reptilians remained loyal no matter what evidence was presented. In an effort to assist the Reptilians in their theft of the final version of the Xindi weapon the Guardians created vast anomalies around some of the spheres, targeting the effects on the ships trying to stop the weapon.  As Captain Archer battled to stop the weapon the NX-01 attacked Sphere 41 in an attempt to disrupt the network and collapse the Expanse once and for all. The Guardians attacked the ship when it entered an anomaly around the sphere, but were unable to prevent it from destroying the sphere. The destruction of the network caused the anomalies of the Expanse to dissipate, ending the Guardian threat once and for all.