Montanus of Toledo clearly reprimands the clergy of Palencia as a metropolitan bishop. Palencia was already a bishopric, but according to the text (donec et consuetus vobis a Domino praeparatur antistes) it was vacant when Montanus wrote his letter (see record [180]).
Galicia was the region of Spain where Priscillianism was especially popular from the very beginning of the controversy, and remained in strength to the 6th c. as attested by not only the letters of Montanus of Toledo, but also the letter of Pope Vigilantius to Profuturus of Braga, and the canons of the first and the Second Council of Braga (for the short survey of the subject and further readings on Galician Priscillianism see Ubric 2015).
The works of Toribius of Astorga directed to Pope Leo are not extant. They are mentioned in Letter 15 (63 in Hispana) of Pope Leo (PL 54, 678B).