When in the later part of the third century B.C. the Romans experienced the overmastering influence of Greek literature, the Greeks had already developed and brought to perfection a wide range of poetic genres from heroic epic and tragedy to scurrilous epigram. The greatest achievements of the Greek city states, notably Athens and the cities of Ionia, were followed in the third century by those of the Hellenistic period of elegance and refinement in Ptolemaic Alexandria. The Romans, although already under Greek influence of many kinds from Sicily and the settlements on the Italian mainland, had developed no indigenous literary culture of their own apart from various rustic measures, and accepted the mature forms of the Greeks of the mainland and of Alexandria with enthusiasm, making them their own. From crude beginnings Latin writers, by a gradually improving process of creative imitation, developed and expanded the main forms, epic, tragedy, comedy and, later, elegy, in such a way that much of Roman literary history may be seen as an attempt to continue and to rival the Greek tradition. But there was one important exception. For the Greeks satire was not an independent literary form. This was a unique Roman invention.