Olive trees are among the oldest known cultivated trees in the world. The botanical progenitor of the olive tree is not accurately known, but it is thought to be the Oleaster Olea Sylvestris which is still grown wild in North Africa, Portugal, Southern France, Italy and by the Black and Caspian Seas.
Genetic and archaeological studies indicate that the original centre of olive cultivation was in the countries of Israel, Lebanon, Cyprus and Crete.

Olive tree cultivation spread to Greece, Italy, and other Mediterranean countries around 600 B.C.  The olive tree was probably brought to the Iberian peninsular by both the Romans and the Moors. This is indicated by the use in Spain and Portugal of both Greco-Roman and Arabic words associated with olives. The olive fruit, for instance, is called "azeitona" in Portuguese, and the olive oil "azeite", which derive from Arabic words, while the tree is called "oliveira" which derives from the Greek "elea".

In the Góis region it is probable that olive cultivation has been practiced for over 2000 years, and was almost certainly undertaken by the Romans:  they considered those who used animal fats instead of olive oil in their diet to be barbarians, and extended olive cultivation to the entire empire under their occupation.

It is possible to find olive trees in the Góis region that are certainly over 400 years old, and possibly much older. Many of the olive groves were planted well over 100 years ago. Although the number of olive trees has reduced over the last 40 years, as the forestry has increased, it is still an important resource for the region. The existing  trees need to be protected, and where the land around them has become overgrown, it is important to clear the area around the trees so that they can continue to flourish.

The machinery to press the olives and extract the oil was probably introduced to the region by the Romans.  It is also likely that the technology for extracting the oil remained basically unchanged until the introduction of electric motors and hydraulic presses.

In the Góis region there are many old olive presses situated by a river or stream, or in some cases, a man-made water course. Although over the last 40 years, many of the smaller presses have become derelict, there are a few community presses still in use. Probably the best example is the press by the river Ceira, north of Cabreira, which still operates every November, pressing the local olives to extract olive oil.

The olive presses in the region traditionally use a water-wheel to drive two granite wheels that crush the olives and stones into pulp. The oil is then extracted by placing the pulp into circular woven bags, stacked one on top of another, sometimes using metal separators, and then pressed. Traditionally, a cantilever system is used: usually a large tree-trunk, one end of which is built into the wall of the press. The beam, usually well over 1 ton in weight, is lifted by a wooden screw at the other end. The olive pulp is placed under the beam, close to the pivot, and then the beam is lowered by the screw. The liquid that is extracted is a mixture of olive oil and water. This is then filtered to remove plant material, and traditionally the oil and water are separated in a large container, with a curved bottom and bottom-tap. Gentle heat can be used to speed the separation process. After the oil and water have separated, the oil rising to the top, the water can be removed by the bottom-tap, and then the oil. (In modern presses this process is carried out using a centrifuge.)

In areas where many villages are a far distance from an olive press, and it would not be viable to bring the olives to the press and then have to return later to collect the oil, overnight accommodation was built. No more than a collection of basic xisto huts, each just big enough for a single person, several of these would be built in a cluster near the press. A good example of this can still be seen at the olive press at Cabreira.

The olive pressing was also seen as a social gathering, and during the evenings there would be singing, story-telling and much drinking of wine and aguardente! Unfortunately, with modern transport and the new co-operative press at Vila Nova do Ceira, the singing and dancing have been replaced by the noise of the centrifuge.