In the Moschiaturo mountain is the source of other principal torrent, the Torbido, which crosses Métole and Potéte to east and to south of Pietraroja and flows in the plane of Civitella Licinio, hamlet of Cusano Mutri in which it meets the Titerno.

Its territory is part of the central-southern zone of the Apennines included between the Mainarde mountains and the Matese massif, inhabited in the antiquity by Pentri Samnites that set their capital in Bojano.

The Roman domination Latinized the Samnium leaving also a greatest influence on Pietraroja dialect,[5] in which it is lost every trace of Oscan language previously spoken by Samnites.

The promise was not kept and they were shot in the place named Aria corta situated behind the town building,[7] After the unification of Italy, Pietraroja has experiment a strong emigration, especially towards the United States.

Due to the strong gradient in its territory, from the 450 m of the place Casolla, near to the fraction "Potéte" to the 1,823 m of Mount Mutria, notable differences in temperature are present, especially in winter.

The main activities concern the sheep-breeding with production of exceptional handmade cheese and lambs, the bovine breeding with production of caciocavallo (called "casecavàgli" in dialect, characteristic oval cheese whose pieces are joined in couple with a rope and hanged on horizontal rods to mature them) and meat and the breeding of swines, at family level, from which are got, after desiccation to the cold and to the firewood smoke and following seasoning, the salted meats and the hams of which Pietraroja goes famous.

Pietraroja has a surface for agricultural use of 1797.99 hectares (as of 2000)[10] Its name probably derives from the Latin petra robia ("red cliff") or from the Spanish equivalent piedra roja or French pierre rouge , due to the presence of some limestone of this colour on the oriental side of the Mutria, that overhangs it.

Here a juvenile dinosaur, the first in Italy, was discovered, in a fossil containing some internal organs: the animal was named Cyrus by media, while its species was called Scipionyx samniticus.

Among the grassy and woody plants are aromatic marjoram ("mairàna" in dialect), oregano, thyme, wild fennel ("fenùcchiu"), anise ("pimpinèlla"), wild mint ("menta sàuza"), those edible chicory, asparagus ("spàracu"), sprout of butcher's broom, water cress ("cannea"), borage ("urràccia"), edible thistle ("càrdu chìnu")], those with edible fruits [the 2 kinds of blackberry bush with the corresponding fruits ("murrìcule"), the raspberries, the strawberries ("fràule"), the cornels ("vrignàli"), the hawthorn prunellas ("trìnche")], those medicinal valerian ("valleriàna"), angelic, gentian, gentianella, camomile ("cammumìlla"), hyssop ("isópu"), milfoil, the flowers dogrose ("rosa janàra"), hollyhock ("mmàrva"), althaea ("malvónu"), wild carnation, iris, cyclamen ("scocciapiàtti"), snowdrop, broom ("jnéstra"), poppy ("papàgnu"), daisy wheel, sweet violet ("viulètta"), primrose ("viòla iànca")], those poisonous belladonna, hemlock, hellebore, equisetum ("córa de órba"), mistletoe ("viscògna")].

Other present kinds are the tree-frog, the green lizard, the toad ("óttu"), the snail (the white one and that great ochre)("ciammétta"), the water snake and the viper.