The Book of Invasions is the only document which gives mention of the Formoris. It describes them as cyclopean beings, with the body or the head of animals and with only "one leg and one arm." Similar descriptions can be found in most of the founding myths of European and other peoples. The war against "Giants" seems to be a traditional part of their birth as a people. This is quite easy to explain by anyone knowing the "tricks" to build up a story. The mythical hero is all the more brave and courageous that he has an impressive opponent. It is very likely that the Formoris depicted as monsters whe nothing more than simple humans.

Where did they come from? Only Ireland seems to have kept any rememberance but it is also the only Celtic land which was never conquered by the Romans and did not suffer a forced conversion to Christianity. This allowed Ireland to preserve a large part of its oral tradition. Since the Celts used not to write down their myths - mostly as a rule imposed by the druidic cast to preserve its own prerogatives and its cultural ascendant - most of these were wiped out by the successive invasions in Gaul, in Spain and in Great-Britain. Nevertheless some elements survived and can provide indications. Heros usually give their names to places or cities and it is quite surprizing to find little mentions of Lug, the most famous hero who fought the Formoris, in Irish places. Such names are plethora on the continent: the Galician city of Lugo is an obvious example, but the cities of Lyons, Loudun, Laon, Leyde, Leignitz and even Saint-Bertrand de Comminges were all initially known as the "Fortress of Lug" (Lugdunum). These names proove the importance of the cult of this "god" - which Julius Ceasar referred to as the "Gallic Mercury", on the continent while it almost does not appear in the British Isles.

It seems possible to deduce from this that the overall myth attched to Lug and including the Formoris was only imported into Ireland and was actually of continental origin. The Daneans would then appear to be part of the early Indo-Europeans, in this case Proto-Celts, fighting with Ligurian and Iberian populations living in Western Europe art that time.

These Iberians, who settled there centuries earlier, should have colonized the Northern coast of Spain, a region with numerous natural harbors. It is thus easy to imagine a people of fishermen, about which we no longer know anything today but which, at the dawn of the Bronze Age, must have been sailing regularly to Brittany, Great-Britain and even Ireland. There is no tangible proof but there might have been our Formoris.