 destroyed their own homeworld. It wasn't an interplanetary holocaust that was not of their own making. They were very similar to us, except they were... They did not have the limitations that we have. They were completely telepathically aware, even back then. But they were very similar to us in the sense they were burning themselves off their own home planet. They basically killed their own planet through wanton abuse of their environment, greed, selfishness, the works.