Most of Ireland is covered with ice until the end of the last ice age over 9,000 years ago.

Sea levels are lower and Ireland, like Great Britain, is part of continental Europe.

Mesolithic stone age inhabitants arrive some time after 8,000 BCE and agriculture follows with the Neolithic Age around 4,500 to 4,000 BCE when sheep, goats, cattle and cereals are imported from the Iberian peninsula.At the Céide Fields, preserved beneath a blanket of peat in present-day County Mayo, is an extensive field system, arguably the oldest in the world, dating from not long after this period.

Consisting of small divisions separated by dry-stone walls, the fields are farmed for several centuries between 3,500 and 3,000 BCE.

Wheat and barley are the principal crops.The Bronze Age – defined by the use of metal – begins around 2,500 BC, with technology changing people's everyday lives during this period through innovations such as the wheel, harnessing oxen, weaving textiles, brewing alcohol, and skillful metalworking, which produces new weapons and tools, along with fine gold decoration and jewelry, such as brooches and torcs.

According to John T. Koch and others, Ireland in the Late Bronze Age is part of a maritime trading-networked culture called the Atlantic Bronze Age that also includes Britain, France, Spain and Portugal where Celtic languages develop.

(Koch, John; Tartessian: Celtic from the Southwest at the Dawn of History in Acta Palaeohispanica X Palaeohispanica 9 (2009)