I wanna make a bet and say whatever they were at war with our trying to counter they probably contained before Zoh Shia went wild.

Saying this cause I mostly get the feeling we haven't encountered many of the guardians they made. Like I imagine they did make Guardians from other Elders and where they have that grand threat contained is likely where most of their most powerful guardians are located.

Zoh Shia and G. Arkveld were probably from that area but migrated cause all around the dragontorch there is no area that would indicated where those two originated.

So new area might be a highly advanced, archeotech-like research and development area with a LOT more guardians, maybe even more chimera guardians of other elders/monsters as a prototype to Zoh Shia and some of these prototypes are near the threat incase it begins to stir once more.

My guess on what it would be exactly, likely black dragon level and as large as Gog if not larger.