Afghanistan (Pashto/Dari: , Afġānistān), officially the Islamic Republic of Afghanistan, is a landlocked country located within South Asia and Central Asia. It has a population of approximately 31 million people, making it the 42nd most populous country in the world. It is bordered by Pakistan in the south and east; Iran in the west; Turkmenistan, Uzbekistan, and Tajikistan in the north; and China in the far northeast. Its territory covers , making it the 41st largest country in the world. Human habitation in Afghanistan dates back to the Middle Paleolithic Era, and the country's strategic location along the Silk Road connected it to the cultures of the Middle East and other parts of Asia. Through the ages the land has been home to various peoples and witnessed numerous military campaigns, notably by Alexander the Great, Muslim Arabs, Mongols, British, Soviet Russians, and in the modern-era by Western powers. The land also served as the source from which the Kushans, Hephthalites, Samanids, Saffarids, Ghaznavids, Ghorids, Khiljis, Mughals, Hotaks, Durranis, and others have risen to form major empires. The political history of the modern state of Afghanistan began with the Hotak and Durrani dynasties in the 18th century. In the late 19th century, Afghanistan became a buffer state in the "Great Game" between British India and the Russian Empire. Following the 1919 Anglo-Afghan War, King Amanullah and King Mohammed Zahir Shah attempted modernization of the country. A series of coups in the 1970s was followed by a Soviet invasion and a series of civil wars that devastated much of the country.