Protohistory of Ireland

Ireland can be said to have had a protohistorical period, when, in prehistory, the literate cultures of Greece and Rome began to take notice of it, and a further proto-literate period of ogham epigraphy, before the early historical period began in the 5th century. Attempts have been made to reconstruct the political developments of this period by reference to early medieval Irish genealogical texts.

Classical writers occasionally refer to Ireland under a variety of names, but these references contain little reliable information. For example, Diodorus Siculus claims that the Prettanoi of the island of Iris eat human flesh.Strabo, who calls the island Ierne, repeats the accusation, adding that they consider it honourable to eat their dead fathers, and openly have sex with their mothers and sisters (although he is sceptical about his sources).Pomponius Mela calls it Iuverna and says that, although the climate is unfavourable for grain, grass grows so richly that cattle burst if unrestrained from eating it.Julius Caesar, in his Commentarii de Bello Gallico, is the first to call the island Hibernia, describes it as about half the size of Britain, and correctly places it to the west of Britain – unlike Strabo, who places it to the north.

Tacitus says that his father-in-law Gnaeus Julius Agricola, while governor of Britain (AD 78-85), considered conquering Ireland, believing it could be held with one legion plus auxiliaries, and entertained an exiled Irish petty king with the intention of making him the pretext for conquest. Parallels have been drawn with the Irish legend of Túathal Techtmar, who is said to have been exiled to Britain as a child and returned with an army to claim the kingship of Tara in the 1st century. Tacitus also says that most of the harbours and approaches to Ireland were known through commerce, but inaccurately locates the island between Britain and the Iberian peninsula.

...
Wikipedia