How about the Duodecim Populi Etruriae, the Latin name for the old Etruscan league of Etruria? Some info from Wiki:

All the city-states of the Etruscans were gathered into confederacies, or “leagues”. The sources tell us there were three. A league for unknown reasons, likely religious, had to include 12 city-states. The word for league was also mech. Once a year the states met at a fanu, or sacred place (Latin fanum) to discuss military and political affairs, and also to choose a lucumo, “ruler”, who held the office for one year. What he did is described by the infinitive, lucair, “to rule.” The Etrurian confederacy met at the fanum Voltumnae, the "shrine of Voltumna". Their league was called the “duodecim populi Etruriae” or the “twelve peoples of Etruria”.