Afghanistan (officially the Islamic Republic of Afghanistan) is a landlocked country in South and Central Asia. With a population of about 28 million, it has an area of 647,500 km sq, making it the 42nd most populous and 41st largest nation in the world. It is bordered by Pakistan in the south and east [note], Iran in the west, Turkmenistan, Uzbekistan and Tajikistan in the north, and the People’s Republic of China in the far northeast. The territory that now forms Afghanistan has been an ancient focal point of the Silk Road and human migration. Archaeologists have found evidence of human habitation from as far back as 50,000 BC. Urban civilization may have begun in the area as early as 3,000 to 2,000 BC.