In 1978, after a second coup Afghanistan first became a socialist state and then a Soviet Union protectorate.
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.
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) may have been a colony of the nearby Indus Valley Civilization.
Its border with British India, the Durand Line, was formed in 1893 but it is not recognized by the Afghan government and it has led to strained relations with Pakistan since the latter's independence in 1947.