Afghanistan has been an ancient focal point of the Silk Road and human migration. Archaeologists have found evidence of human habitation from as far back as the Middle Paleolithic. Urban civilization may have begun in the area as early as 3,000 to 2,000 BC.[10] Sitting at an important geostrategic location that connects the Middle East culture with Central Asia and the Indian subcontinent,[11] the land has been home to various peoples through the ages[12] and witnessed many military campaigns, notably by Alexander the Great, Genghis Khan, and in modern era Western forces.[10] The land also served as a source from which the Greco-Bactrians, Kushans, Hephthalites, Saffarids, Ghaznavids, Ghorids, Mughals, Durranis, and others have risen to form major empires.
.......
Excavations of prehistoric sites by Louis Dupree and others 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 terms of the historical value of its archaeological sites.
The country sits at a unique nexus point where numerous civilizations have interacted and often fought. It has been home to various peoples through the ages, among them the ancient Iranian peoples who established the dominant role of Indo-Iranian languages in the region. At multiple points, the land has been incorporated within large regional empires, among them the Achaemenid Empire, the Macedonian Empire, the Indian Maurya Empire, the Islamic Empire and the Sassanid Empire.
http://en.wikipedia.org/wiki/Afghanistan