Pakistan, officially the Islamic Republic of Pakistan, is a country in South Asia. It is the sixth-most populous country with a population exceeding 199 million people. It is the 36th largest country in the world in terms of area with an area covering 881,913 km2. Pakistan has a 1046km coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by India to the east, Afghanistan to the west, Iran to the southwest and China in the far northeast respectively. It is separated from Tajikistan by Afghanistan's narrow Wakhan Corridor in the north, and also shares a maritime border with Oman.The territory that now constitutes Pakistan is considered a cradle of civilization which was previously home to several ancient cultures, including the Mehrgarh of the Neolithic and the Bronze Age Indus Valley Civilisation, and was later home to kingdoms ruled by people of different faiths and cultures, including Hindus, Indo-Greeks, Muslims, Turco-Mongols, Afghans and Sikhs. The area has been ruled by numerous empires and dynasties, including the Indian Mauryan Empire, the Persian Achaemenid Empire, Alexander of Macedonia, the Arab Umayyad Caliphate, the Delhi Sultanate, the Mongol Empire, the Mughal Empire, the Durrani Empire, the Sikh Empire and the British Empire.