In 283 BC unspecified Gauls besieged the city of Arretium (
Arezzo, in north-eastern Tuscany) and defeated a Roman force which had come to the aid of the city. The subsequent actions are reported differently by
Polybius and
Appian. In any case the Romans then invaded the territory of the Senones, killed most of them, drove the rest out of the country. The territory had earlier been part of
Picenum but was then annexed by the Romans and became an
ager publicus (Roman state land) and they made the town at
Sena Gallica a colony. In order to control the population and mercantile activities of the Ager, the Romans also founded the coastal colonies of
Ariminum (
Rimini),
Pisaurum (
Pesaro) and
Fanum Fortunae (
Fano). The administration of the inland was organized in 232 BC by the
Lex Flaminia de agro Gallico et Piceno viritim dividendo, which created a network of prefectures (
praefecturae), some of which, in the mid-1st century BC, were granted the status of
municipia:
Aesis (
Iesi),
Suasa,
Ostra, and
Forum Sempronii (
Fossombrone). The construction, in 220 BC, of the
Via Flaminia shifted the relative position of the Ager, which was now connected to the seat of power by the consular road that traversed it along the
Metauro river valley.
Later administrative organisation After the Augustan administrative reorganization of the Italian peninsula, the
Ager Gallicus was united with
Umbria and became part of the
Regio VI Umbria et Ager Gallicus. The
Diocletian reform of 300 AD split the Ager from Umbria, and combined with the Picenum to become the province
Flaminia et Picenum. Later, under emperor
Theodosius I, the territory was split again (this time from Picenum, which became the province of
Picenum Suburbicarium), and became part of the province of
Flaminia et Picenum Annonarium. Some scholars see in this new name, which for the first time included the word "Picenum", as an acknowledgement (albeit belated) by Rome of the Italic people known as the
Piceni, which had lived in the area between the 10th and 4th century BC. ==References==