We know those drones attack any thing that is advanced technology, thats what they were programmed to do. Whoever built them wanted to take down either one advanced enemy or cleanse the galaxy from advanced technology. We were told they were part of a war. The Ursini became extinct after they awoken the drones. So the drones are much older and were used in a war that probably had the two sides extinct. Could one of the races who created the drones be the God-like planet builders? They probably evolved into being energy based species who for some reason are unlike the ancients. But its more likely they were the ones who created the universe and are closely related to the signal Rush is after. So why would those extra-dimensional beings create these drones? I believe they were set up to prevent a future occurrence, to guard that part of the galaxy from approaching armies. Could you buy that theory? That they were intended as a force for good?