The fact is of course obvious that the normal unit of organised society in the area of the Graeco-Roman civilisation was the partly autonomous town. In very early times the towns in Italy were grouped in Leagues which were based generally on racial affinities; and the same was the case with the towns in the lands outside Italy which were earliest conquered by Rome. One of the commonest features of early alliances was the allowance of what the Romans called the “ius exilii” that is to say, each of the contracting parties agreed to give a harbourage to those citizens of its ally who were driven out by internal commotions. Exile was an exceedingly common incident of public life in the early days of an ancient town. It may be said that in primitive times party politics were not carried on by strife between two sections within the city walls. Rather one of the contending parties was within the walls, while the other was outside, anxious to force an entry and eject its opponents. It is probable that the ius exilii had a very considerable effect in early days in shifting population.