 To the extent that sources are available, they depict a pre-Christian Iron Age Celtic social structure based formally on class and kingship, although this may only have been a particular late phase of organization in Celtic societies.Patron-client relationships similar to those of Roman society are also described by Caesar and others in the Gaul of the 1st century BC.In the main, the evidence is of tribes being led by kings, although some argue that there is also evidence of oligarchical republican forms of government eventually emerging in areas which had close contact with Rome.