On top of civilizations, there exist four metacivilizations, of which every one presents a system of two civilizations connected with each other historically and culturally. “Islandmanship” is inherent not only to Russia, but also to all other civilizations, and the Great Limitrophe only partly lies along the perimeter of the cultural boundaries of Russia: it divides the metacivilizations of the Old World. Especially important within its composition is the part that stretches from the Balkans to Kashgaria, forming the “back bone” of the Great Limitrophe (BBGL). The BBGL plays a key role in the history and geopolitics of the whole world. The major part of the limitrophe areas of the Old and New Worlds are related, by their geological origin, to the Thetis prehistoric ocean.