The Sabelli were ancient people if Italy, made up primarily of Samnites and Sabines. The word Sabelli actually means "people who speak Oscan" (a language only slightly more dead than Latin), but the Sabelli were not just connected by language.
They first came on the scene around 5th century B.C. and began expanding westward, assimilating other small tribes and imposing their language on them in the process. They conquered Campania in 450 BC, Lucania in 420 BC, and Brutti somewhere around 356 BC.
The Sabelli people headquartered up at the ancient city of Nola. They were led by a small group of men known as the meddixes (or medixes), but in general they showed little prowess for civic life. They were merely restless marauders, and to prove it, they invaded the Roman Empire in 327 BC.
The Samnites sent troops to Neapolis (modern-day Naples), but were expelled by Roman garrisons a short time later. A border war lasted for several years, with a few major skirmishes, including a heavy defeat of the Romans at Caudine Forks. Finally in 316, the Samnites broke through, capturing large parts of western Italy, but 12 years later, the Romans took Nola and forced a surrender. Afterwars the Samnites were allies of Rome.
Essentially, the lack of political unity among the Sabelli - dating back to their earliest ancestors who, like Mexico and Spain, spoke the same language but had little in common - caused the region to factionalize in a relatively short amount of time, replaced by the Etruscan people who conquered and settled Rome near 100 BC. There, after a gruesome battle, the remaining men of the Sabelli (as all men were soldiers) were captured by Sulla and imprisoned. Two days later, Sulla placed them in a large public circus maximus and had his soldiers attack them while they were unarmed. There were no survivors. Sulla claimed:
From experience, not a Roman could ever live in peace so long as the Samnitae held together as a separate people.
The famous painting The Rape of the Sabine Women by Nicholas Poussin (and perhaps its even more famous interpretation by Pablo Picasso) is a depiction of the Roman border war with the Sabelli.