Regions or pays as Vidal de la Blache called them are human constructs in the study of Geography and help us look at spatial extents. Regions are worlds within worlds.
Historical regions are regions delimited for studying the social development of period-specific cultures without any reference to contemporary political, economic or social organisations.
The real idea behind this type of delimitation is that older political and mental structures remain in place which exercise greater influence on the spatial social identity of individuals than is understood by the today’s world, bound to and often blinded by its own worldview(e.g. the focus on the nation-state).
Definitions of regions vary to a great extent. Regions can include macroregions such as Europe, territories of traditional states or smaller micro-regional areas.
A geographic proximity is the precondition for the emergence of a region. In Europe, the regional identities are derived from the Migration Period.
Some regions( rather the name of the region) are entirely invented, such as the Middle East in 1902 by a military strategist and political geographer, Alfred Thayer Mahan, to refer to the area of the Persian Gulf.