The Nishadha (IAST: Niṣadha) was a tribe of ancient India that lived in a country of the same name[1][2]
The Niṣādas are surely quite distinct from the Niṣādhas, with whom they are often confounded but who in all probability belonged to the Aryan fold.
The Niṣādhas, residing in the Niṣādha country were obviously Aryan tribes and they should not be confused with the Niṣāda, the non-Aryan tribe.