In response to the emergence of the ethnic nationalism with increasing separatist tendencies in Catalonia and the Basque Country at the turn of the 20th century Juan Vàsquez de Mella – the main theorist of Carlism (Carlismo) – redefined the traditionalist concept of Spanish regionalism that positioned itself equally distinctly from the liberal centralism and from the separatism of regional nationalisms. The core of this concept was the treatment of each region as a relatively autonomous community, yet linking its unique lifestyle with the others in the spirit of unity combining all regions with what is common and supreme, i.e. the nation and the state. Spain is hence the federation of regions who share – despite their specific characteristics – the common history and who belong to the same civilisation (hispanidad), itself inseparable from the Christianity (cristiandad). Separatism – as a selfish refusal to share this destiny with other regions – is considered by the author as an unacceptable attitude, comparable – depending on the degree and consequences of the said separation – with schism, heresy or even religious apostasy. On the other hand, Vàsquez de Mella granted the state the sovereign authority exclusively in the area of the relations with the Church, foreign policy, army command, public order as well as the intermediation and arbitration between the regions and social classes, leaving all the other competences with the local, trade and provincial communities.