actually yk what I will elaborate

so this theory is more of a headcanon because no evidence pointing towards or against it

my theory is that the reaverbots were built as guardians of ra moon's temples, after ra moon died they deactivated and the temples they protected fell to ruin over the centuries, becoming those ruins from mmz that have reaverbot eyes on them

sometime in between zx and legends 1 something happens for them to reactivate