The first known inhabitants of the Dublin region were hunter-gatherers living during the Later Mesolithic, or Middle Stone Age, around 5500 BC. Shell middens and occupation debris, which have been found at a number of locations on and around the shores of Dublin Bay (most notably at Sutton and on Dalkey Island), indicate that these early settlers lived off the sea.
The first farmers appeared in the Neolithic, or New Stone Age, shortly after 4000 BC. These were the first to erect megalithic monuments and evidence of their culture survives in the burial cairns, passage tombs, portal tombs and wedge tombs that can still be seen in the Dublin Mountains and on the coastal lowlands just to the south of the modern city. Stone axes made of porcellanite from County Antrim or porphyry from Lambay Island have also been discovered at a number of sites in the Dublin region. Pottery too was first manufactured in Ireland during the Neolithic, one of the most noteworthy finds being a funerary bowl which was found in a burial site at Drimnagh, County Dublin.
Around 2400 BC metal working made its first appearance in Ireland. Archaeological excavations in Suffolk Street have uncovered prehistoric copper axe-heads – the copper axe being the principal metal artifact during the earliest phase of Irish metallurgy (the so-called Knocknagur Phase, or Copper Age, which lasted from 2400–2200 BC).
The Bronze Age, which in Ireland is dated from 2200–600 BC, also left its mark on the Dublin region. A variety of bronze and gold artifacts which have been discovered in the vicinity of the modern city – among them cauldrons, side-blown horns, lock rings, sleeve fasteners, striated rings, hair rings and penannular bracelets – indicate a continuous or intermittent settlement of the area.
In Ireland the commencement of the Iron Age around 600 BC is generally believed to coincide with the first appearance in this country of Celtic-speaking peoples. There is little archaeological evidence to support the theory of a large-scale Celtic invasion (or series of invasions), but it is quite possible that small groups of migrants, highly skilled in the art of war and armed with superior iron weaponry, were powerful enough to gain a foothold in the island and eventually succeeded in subjugating or absorbing the pre-Celtic natives; in the 12th century of the Common Era small bands of heavily armed Anglo-Normans did just this, so there is no conceivable reason why it could not also have happened in the pre-Christian era.
Iron ores are widely distributed throughout Ireland – one of the country’s two richest deposits is to be found in County Wicklow, just a few days’ walk from the Dublin region – but there is little archaeological evidence for an urban settlement on the site of the modern city during the Early Iron Age (or Athlone Phase). Excavations at various locations in the region, however, do indicate intermittent occupation at scattered locations throughout this period (e.g. at Taylor’s Grange in Rathfarnham, and at Cherrywood near Loughlinstown).
Once associated with the Iron Age is the ringfort, or ráth, a defensive formation generally consisting of one or more circular earthen embankments surrounded by a ditch. The existence of ringforts in the Dublin region may be deduced from the names of several of the modern city’s suburbs: Rathmines, Rathgar, Rathfarnham (on the south side of the city) and Raheny (on the north side). There is also the village of Rathcoole, which lies to the southwest of the modern city. Needless to say the growth of the modern city has all but obliterated these structures, but excavation of ringforts in other parts of the country has sometimes revealed traces of earlier, pre-ringfort occupation of the same sites. In the Dublin hinterland, surviving ringforts are too numerous to mention individually, though a univallate ringfort at Rathmichael (near Shankill to the southeast of the city) may be noted. The lowlying area to the northwest of the city is particularly rich in ringforts. It is now thought, however, that most of Ireland’s ringforts date from the Christian era