the major geostrategic doctrines in the discipline's history. While there have been many other geostrategists, these have been the most influential in shaping and developing the field as a whole. Alfred Thayer Mahan Alfred Thayer Mahan was a U.S. Navy officer and president of the Naval War College. He is best known for his Influence of Sea Power upon History series of books, which argued that naval supremacy was the deciding factor in great power warfare. In 1900, Mahan's book The Problem of Asia was published. In this volume he laid out the first geostrategy of the modern era. The Problem of Asia divides the continent of Asia into 3 zones: A northern zone, located above the 40th parallel north, characterized by its cold climate, and dominated by land power; The "Debatable and Debated" zone, located between the 40th and 30th parallels, characterized by a temperate climate; and, A southern zone, located below the 30th parallel north, characterized by its hot climate, and dominated by sea power. The Debated and Debatable zone, Mahan observed, contained two peninsulas on either end (Anatolia and the Korea), the Isthmus of Suez, Palestine, Syria, Mesopotamia, two countries marked by their mountain ranges (Persia and Afghanistan), the Pamir Mountains, the Tibetan Himalayas, the Yangtze Valley, and Japan. Within this zone, Mahan asserted that there were no strong states capable of withstanding outside influence or capable even of maintaining stability within their own borders. So whereas the political situations to the north and south were relatively stable and determined, the middle remained "debatable and debated ground." North of the 40th parallel, the vast expanse of Asia was dominated by the Russian Empire. Russia possessed a central position on the continent, and a wedge-shaped projection into Central Asia, bounded by the Caucasus Mountains and Caspian Sea on one side and the mountains of Afghanistan and Western China on the other side. To prevent Russian expansionism and achievement of predominance on the Asian continent, Mahan believed pressure on Asia's flanks could be the only viable strategy pursued by sea powers. South of the 30th parallel lay areas dominated by the sea powers – the United Kingdom, the United States, Germany, and Japan. To Mahan, the possession of India by the United Kingdom was of key strategic importance, as India was best suited for exerting balancing pressure against Russia in Central Asia. The United Kingdom's predominance in Egypt, China,