Afghanistan is a landlocked country located at the crossroads of Central and South Asia. Afghanistan borders Pakistan to the east and south, China to the northeast, Iran to the west, and Turkmenistan, Uzbekistan, and Tajikistan to the north. Because of its strategically important location connecting the Middle East, India, and the Eurasian Steppe, Afghanistan served as a central gateway on the ancient Silk Road, the famous trade route stretching from the Mediterranean Sea to China. The earliest human traces in the region of Afghanistan go back at least 52,000 years. The earliest written record can be traced back to around 500 BC - the time of the Achaemenid Empire. Today Afghanistan is an Islamic nation, in which over 90% of the population follow Sunni Islam, about 10% are Shia Muslims, and a small percent follow other religions such as Zoroastrianism, Sikhism, Buddhism, Jainism, and Hinduism. Afghanistan is famous for cherished historical sites including forts, minarets, castles, statues, and palaces, as well as ancient crafts, and a variety of art forms. The Citadel of Herat, located in the center of Herat in the fertile Hari River Valley, is also known as the Citadel of Alexander. Between 1976 and 1979, the historic Citadel was excavated and restored by UNESCO, and after experiencing decades of conflict, several international organizations decided to rebuild it. In the historical trade center of Ghazni city, the Ghazni Minarets, the only architectural remnants of the Bahram Shah Mosque and artifacts of the great Ghaznavid Empire, are two elaborately decorated towers built of fired mud bricks in the middle of the 12th century. The Minaret of Jam, a UNESCO World Heritage Site, is located in a remote region of the Ghor Province in western Afghanistan. The Minaret of Jam was built of intricate baked bricks around the year 1190 as a monument of the Ghorid Empire.