Around 4000 B.C.E., things changed. People began to grow food and make pottery. They cleared forests for their fields and built more permanent settlements. Archaeologists call this new period the Neolithic Period, or New Stone Age.

It's possible that the Mesolithic Irish developed this new technology on their own, but it's more likely that these changes came over the ocean with new immigrants. The newcomers either conquered the people already living there, or, more likely, they just assimilated them, intermarrying and sharing techniques for making tools and growing food.

Neolithic people built their houses out of wood. These houses have mostly decayed, but their foundations are still visible. Archaeologists have also found lots of new tools for grinding wheat and a huge number of polished stone axes made from a stone called porcellanite.