The origin of Alcains is particulary on to the development of the agricultural exploration of the fields, a time that the locality if finds between streams being the stream of the Líria the predominant water course.

It is not obtained however to date in very rigorous way the birth of the town.

Some studious places make to retrace the existence of Alcais the Roman times, for having in one definitive zone (in the way for the hermitage of Sta. Apolónia) a related way to the ways left for the Romans in some points of the country.

Another possible date meets in the proper name of the locality: Alcains, enrolled in the toponimy of Arab origin. It will be, then, possible to bind the setting of the town to the period of Arab occupation.

The currents limits of Alcains, were enclosed in the Iberian Peninsula , this enclosed the space of currently busy for Portugal and Spain . Its village was made by tribes of the neolithic time according to archaeological data.

Also numerous vestiges of the Roman period had been found, such as a Roman oven in the called place of Bare Head and two roads Romans a coming of Castelo Branco and following for north and another coming of Castile, passing for the Egitânea (Idanha-a-Nova), following for Saint Vicente da Beira in direction the Coimbra.

The influence of the Arabs is well-known in Alcains, until the name is of Arab origin, Alcaien what it means Existing or Permanent, as based Loyal Pine as of custom, in Frei Luis de Sousa.