Sir Halford Mackinder was a British geographer and politician known for his influential theories on geopolitics in the early 20th century. He is best known for his concept of the "Heartland," which he described as a central region of Eurasia that holds significant strategic importance. Mackinder argued that whoever controls this area would dominate the world. Mackinder's ideas were presented in his 1904 paper, "The Geographical Pivot of History," where he emphasized the importance of geography in global power dynamics. His theories have influenced military strategy and international relations, particularly during the Cold War and beyond, as nations sought to secure their interests in the Heartland region.