Human habitation in Afghanistan dates back to the Middle Paleolithic Era, and the country's strategic location along the Silk Road connected it to the cultures of other parts of Asia as well as Europe; its location on the Asian land routes has been described the "roundabout of the ancient world", leaving behind a mosaic of ethnolinguistic and religious groups that has influenced present Afghanistan. The land has historically been home to various peoples and has witnessed numerous military campaigns, including those by Alexander the Great, Mauryas, Muslim Arabs, Mongols, British, Soviets, and Americans (with coalition allies). It is nicknamed the "graveyard of empires", though it has been occupied during several different periods of its history. The land also served as the source from which the Greco-Bactrians, Kushans, Hephthalites, Samanids, Saffarids, Ghaznavids, Ghorids, Khaljis, Mughals, Hotaks, Durranis, and others have risen to form major empires. The various conquests made the area a center for Buddhism, Zoroastrianism, Hinduism and Islam throughout history.