Associations in ancient Rome
In ancient Rome, the principle of private association was recognized very early by the state. Sodalitates for religious purposes are mentioned in the Twelve Tables, and collegia opificum, or trade guilds, were believed to have been instituted by Numa Pompilius, which probably means that they were regulated by the jus divinum as being associated with particular cults.
Source: Wikipedia — Associations in ancient Rome (CC BY-SA 4.0)