In 1540 under the episcopate of Rinaldo de' Cancellieri, it was united to the Diocese of Bisaccia (the ancient Romulea); it appears first as a bishopric in 1179.
The main centres of the Hirpini were Malies or Maloenton (modern Benevento), Romulea (Bisaccia), Compsa (Conza), Aquilonia, Lacedonia and Abellinum (Avellino).
Montenero di Bisaccia borders the following municipalities: Cupello, Guglionesi, Lentella, Mafalda, Montecilfone, Palata, Petacciato, San Felice del Molise, San Salvo, Tavenna.