Soria is a province of central Spain, in the eastern part of the autonomous community of Castile and León. Most of the province is in the mounta…Soria is a province of central Spain, in the eastern part of the autonomous community of Castile and León. Most of the province is in the mountainous Sistema Ibérico area. It is bordered by the provinces of La Rioja, Zaragoza, Guadalajara, Segovia, and Burgos. Soria is the least populous of all of Spain's provinces, with a density of around 9 inhabitants/km²—one of the lowest in the European Union. The average population density of provinces in Spain and European Union are 83.6 and 116 inhabitants per square km respectively. In comparison, the Soria province is less dense than some northern parts of the Nordic countries.