Pollen analysis
Pollen analysis confirms the Iron Age as a period of intense deforestation in Galicia and Northern Portugal, with meadows and fields expanding at the expense of woodland. Using three main type of tools, ploughs, sickles and hoes, together with axes for woodcutting, the Castro inhabitants grew a number of cereals: (wheat, millet, possibly also rye) for baking bread, as well as oats and barley which they also used for beer production. They also grew beans, peas and cabbage, and flax for fabric and clothes production; other vegetables were collected: nettle, watercress. Large quantities of acorns have been found hoarded in most hill-forts, as they were used for bread production once toasted and crushed in granite stone mills.