Excavations of prehistoric sites suggest that humans were living in what is now Afghanistan at least 50,000 years ago, and that farming communities in the area were among the earliest in the world. An important site of early historical activities, many believe that Afghanistan compares to Egypt in the historical value of its archaeological sites.[50][51] Artifacts typical of the Paleolithic, Mesolithic, Neolithic, Bronze, and Iron Ages have been found in Afghanistan. Urban civilization is believed to have begun as early as 3000 BCE, and the early city of Mundigak (near Kandahar in the south of the country) was a center of the Helmand culture. More recent findings established that the Indus Valley Civilization stretched up towards modern-day Afghanistan. An Indus Valley site has been found on the Oxus River at Shortugai in northern Afghanistan.[52][53][54] After 2000 BCE successive waves of semi-nomadic people from Central Asia began moving south into Afghanistan; among them were many Indo-European-speaking Indo-Iranians. These tribes later migrated further into South Asia, Western Asia, and toward Europe via the area north of the Caspian Sea. The region at the time was referred to as Ariana.[50][55] By the middle of the 6th century BCE, the Achaemenids overthrew the Medes and incorporated Arachosia, Aria, and Bactria within its eastern boundaries. An inscription on the tombstone of Darius I of Persia mentions the Kabul Valley in a list of the 29 countries that he had conquered.[56] The region of Arachosia, around Kandahar in modern-day southern Afghanistan, used to be primarily Zoroastrian and played a key role in the transfer of the Avesta to Persia and is thus considered by some to be the "second homeland of Zoroastrianism".[57][58][59] A "Bactrian gold" Scythian belt depicting Dionysus, from Tillya Tepe in the ancient region of Bactria Alexander the Great and his Macedonian forces arrived in Afghanistan in 330 BCE after defeating Darius III of Persia a year earlier in the Battle of Gaugamela. Following Alexander's brief occupation, the successor state of the Seleucid Empire controlled the region until 305 BCE, when they gave much of it to the Maurya Empire as part of an alliance treaty. The Mauryans controlled the area south of the Hindu Kush until they were overthrown in about 185 BCE. Their decline began 60 years after Ashoka's rule ended, leading to the Hellenistic reconquest by the Greco-Bactrians. Much of it soon broke away and became part of the Indo-Greek Kingdom. They were defeated and expelled by the Indo-Scythians in the late 2nd century BCE.[60][61] The Silk Road appeared during the first century BCE, and Afghanistan flourished with trade, with routes to China, India, Persia, and north to the cities of Bukhara, Samarkand, and Khiva in present-day Uzbekistan.[62] Goods and ideas were exchanged at this center point, such as Chinese silk, Persian silver and Roman gold, while the region of present Afghanistan was mining and trading lapis lazuli stones[63] mainly from the Badakhshan region. During the first century BCE, the Parthian Empire subjugated the region but lost it to their Indo-Parthian vassals. In the mid-to-late first century CE the vast Kushan Empire, centered in Afghanistan, became great patrons of Buddhist culture, making Buddhism flourish throughout the region. The Kushans were overthrown by the Sassanids in the 3rd century CE, though the Indo-Sassanids continued to rule at least parts of the region. They were followed by the Kidarites who, in turn, was replaced by the Hephthalites. They were replaced by the Turk Shahi in the 7th century. The Buddhist Turk Shahi of Kabul was replaced by a Hindu dynasty before the Saffarids conquered the area in 870, this Hindu dynasty was called Hindu Shahi.[64] Much of the northeastern and southern areas of the country remained dominated by Buddhist culture.[65][66] Medieval period Main articles: Muslim conquests of Afghanistan, Mongol campaigns in Central Asia, and Ghaznavid campaigns in India The Ghurids originated from Ghor Province in central Afghanistan. Arab Muslims brought Islam to Herat and Zaranj in 642 CE and began spreading eastward; some of the native inhabitants they encountered accepted it while others revolted. Before the arrival of Islam, the region used to be home to various beliefs and cults, often resulting in Syncretism between the dominant religions[67][68] such as Zoroastrianism,[57][58][59] Buddhism or Greco-Buddhism, Ancient Iranian religions,[69] Hinduism, Christianity,[70][71] and Judaism.[72][73] An exemplification of the syncretism in the region would be that people were patrons of Buddhism but still worshipped local Iranian gods such as Ahura Mazda, Lady Nana, Anahita or Mihr (Mithra) and portrayed Greek gods as protectors of Buddha.[74][69][75] The Zunbils and Kabul Shahi were first conquered in 870 CE by the Saffarid Muslims of Zaranj. Later, the Samanids extended their Islamic influence south of the Hindu Kush. The Ghaznavids rose to power in the 10th century.[76][77][78] By the 11th century, Mahmud of Ghazni had defeated the remaining Hindu rulers and effectively Islamized the wider region,[79] with the exception of Kafiristan.[80] Mahmud made Ghazni into an important city and patronized intellectuals such as the historian Al-Biruni and the poet Ferdowsi.[81] The Ghaznavid dynasty was overthrown by the Ghurids in 1186, whose architectural achievements included the remote Minaret of Jam. The Ghurids controlled Afghanistan for less than a century before being conquered by the Khwarazmian dynasty in 1215.[82] Mongol invasions and conquests In 1219 CE, Genghis Khan and his Mongol army overran the region. His troops are said to have annihilated the Khwarazmian cities of Herat and Balkh as well as Bamyan.[83] The destruction caused by the Mongols forced many locals to return to an agrarian rural society.