Tribes () were groupings of citizens in ancient Rome, originally based on location. Voters were eventually organized by tribes, with each Roman tribe having an equal vote in the Tribal Assembly.
Latin tribus perhaps derives from the Latin word for "three", trÃÂs. The Romans believed that through much of the early regal period of Roman history, there were only three tribes:
These names were also preserved in the names of six of the later centuries of Roman equites.
Livy records that in 495 BC the number of tribes was increased to 21, and the number of tribes reached 35 in 242 BC and was not expanded further.
Attributed by Livy to the sixth Roman king, Servius Tullius, the urban tribes were named for districts of the city and were the largest and had the least political power. In the later Republic, poorer people living in the city of Rome itself typically belonged to one of these tribes. Freedmen were also traditionally assigned to one of these tribes.
Landowners and aristocracy traditionally belonged to the 31 smaller rural tribes. Many rural tribes derive from prominent Roman gentes, or family names, such as Cornelia or Fabia.
There was an official order of the tribes. Literature and archaeological documentation show that the urban tribes are enumerated according to a counter-clockwise circuit of the city. On that basis, Lily Ross Taylor suggested that the same held for the rural tribes.
Archaeological findings of tesserae led Michael Crawford to suggest that the tribes were ordered according to the principal roads leading counter-clockwise from Rome (Ostiensis, Appia, Latina, Praenestina, Valeria, Salaria, Flaminia and Clodia).