The stone age is divided into the palaeolithic (to c.9000 bce), mesolithic (c.9000–7000 bce) and neolithic (7th–4th millennia bce); *metallurgy began during the neolithic, before the conventional neolithic–bronze age transition.Classical Greece was an essentially agricultural society and as such can trace its origins back to the first farming communities in Greece in the early neolithic (7th millennium bce). Some at least of the domestic livestock and crop species were introduced from the near east, but Greece had long been occupied by palaeolithic and mesolithic gatherer-hunters (e.g. at Franchthi cave, Argolid). It is unclear whether the first farmers were of indigenous, immigrant or mixed stock. Known early farming settlements (e.g. Argissa) are heavily concentrated in the fertile lowlands of the eastern mainland, particularly in *Thessaly. The southern mainland and smaller Aegean islands, the heartland of both bronze age palatial civilization and the Classical *polis, were not widely colonized by farmers until the later neolithic and early bronze age (5th–3rd millennia bce).