This new power did not take its rise among those who had hitherto been the most formidable foes of Greece—the Sabello-Oscan tribes, whom Plato dreaded. These last were a race of warlike mountaineers living under a free system of tribal government, something like the Swiss of the later Middle Ages, except that cavalry, as well as infantry, played an important part in their armies. Like the Swiss, they strove to extend their borders on every side beyond the narrow limits of their native land. But they lacked what the Swiss of the Four Cantons gained by their league with Berne and Zurich—a steady political aim; tribe jostled tribe, the remoter endeavouring to wrest from the nearer what the latter had won. Thus, though they might subjugate cities of Greece, they were incapable of creating a great homogeneous state. The Caraceni, Pentri, Caudini, and Hirpini, the four tribes of the mountain tract about the sources of the Volturnus and its tributaries, were the only ones which constituted a compact federation. After the middle of the fourth century these tribes began to press forward in every direction, against the Apulians to the east, the Lucanians to the south, the Campanians, Sidicinians, and Volscians to the west. But there they were confronted by a power which was destined to prove greater than they.
As early as the sixth century, during the Etruscan period, the city of Rome on the Tiber had grown into a large and important community. After the overthrow of foreign dominion and the fall of the monarchy, it maintained its supremacy over at least the majority of the country townships of the little Latin nation, which laboriously warded off the attacks of its neighbours under Roman hegemony. Not till about the year 400 did it succeed in driving the Æqui and Volscians back into their mountain fastnesses; and in 388 it took the neighbouring Etruscan city of Veii. The great Celtic invasion brought it to the verge of ruin; but having survived this peril it maintained its former predominance after the withdrawal of the enemy. With the Greeks it was on friendly terms; from of old, Greek civilisation had found almost as ready acceptance among the Latins as among the Etruscans, and in the struggle with the latter people Latins and Greeks had fought side by side. The middle of the fourth century witnessed a great expansion of Roman power; the Romans conquered the Volscians and several refractory Latin cities, and vanquished their Etruscan neighbours, and in the year 350 the Etruscan city of Cære joined the Roman confederacy. At the same time Rome extended her dominion in the valley of the Liris and towards the coast; and in the latter quarter the great city of Capua (together with Cumæ, now an Oscan city, and many others) threw themselves into the arms of Rome for protection against the Samnites. Soon after, in 336-334, Capua and the Latin towns, which had revolted, were completely subjugated, and most of them incorporated into the Roman body politic. Peace had been maintained up to this time with the Samnites, to whom the south of the Campania and the valley of the upper Liris had been abandoned; but when, in 325, Rome gained a footing in Fregellæ and took the Greeks of Naples under her protection, an open conflict broke out between the two states, each of which was doing its utmost to extend its borders in Italy.