In 1904, during a lecture at the Royal Geographical Society, the British geographer and politician Halford J. Mackinder presented his most famous theory: The Geographical Pivot of History, destined to redefine global strategic thinking. At the centre of his model is the Heartland - roughly identified with Russia and Central Asia - a vast region inaccessible by sea, but rich in natural and energy resources and difficult to conquer. According to Mackinder, in a world increasingly interconnected by land transport (such as railways, e.g. the Trans-Siberian), control of this area represented the key to global domination. His famous formula sums up this vision: "He who dominates Eastern Europe commands the Heartland; he who dominates the Heartland commands the World-Island; he who commands the World-Island controls the world." By World-Island Mackinder meant Eurasia, from Iran to Siberia: the geopolitical core of the planet, where most of the population, resources and arable land are concentrated. In this perspective, maritime powers - such as Great Britain or the United States - risked being undermined by a continental power capable of unifying and dominating the Heartland, like Tsarist Russia in the early 20th century. Mackinder's insight profoundly influenced British and US strategies in the 20th century and was reinterpreted during the Cold War to justify the containment of the Soviet Union, such as George Kennan's famous containment theory and Nicholas Spykman's Rimland theory. Of course, Mackinder's idea was designed to stimulate an aggressive foreign policy on the part of the British Empire to contain Russia, especially in the last years of the Great Game, the geopolitical clash between the two powers for control of Central Asia that ended with the Anglo-Russian Agreement of 1907.