IIRC, horses. Cavalry can't be used around elephants unless the horses are specifically trained to be around elephants. Rome itself of the Republican/early Imp

IIRC, horses. Cavalry can't be used around elephants unless the horses are specifically trained to be around elephants. Rome itself of the Republican/early Imperial era didn't use cavalry, although some of their allies did. As a hypothesis, those using elephants may have been fighting entities that used cavalry.