Afghanistan,[c] officially the Islamic Emirate of Afghanistan,[d] is a landlocked country located at the crossroads of Central Asia and South Asia. Referred to as the Heart of Asia, it is bordered by Pakistan to the east and south,[e] Iran to the west, Turkmenistan to the northwest, Uzbekistan to the north, Tajikistan to the northeast, and China to the northeast and east. Occupying 652,864 square kilometers (252,072 sq mi) of land, the country is predominantly mountainous with plains in the north and the southwest, which are separated by the Hindu Kush mountain range. As of 2021[update], its population is 40.2 million (officially estimated to be 32.9 million), composed mostly of ethnic Pashtuns, Tajiks, Hazaras, and Uzbeks. Kabul is the country’s largest city and serves as its capital.