It seems to me that the Chamus (armies) of the Bharatas have already run away in all directions, being terrified at the clatter of Arjuna's chariot wheels.
अपि तद्रथघोषेण भयार्ता सव्यसाचिनः। प्रतिभाति विदीर्णेव सर्वतो भारती चमूः॥