The history of Afghanistan as a state began in 1823 as the Emirate of Afghanistan after the exile of the Sadozai monarchy to Herat. The Sadozai monarchy ruled the Afghan Durrani Empire, considered the founding state of modern Afghanistan. The written recorded history of the land presently constituting Afghanistan can be traced back to around 500 BCE when the area was under the Achaemenid Empire, although evidence indicates that an advanced degree of urbanized culture has existed in the land since between 3000 and 2000 BCE. Bactria dates back to 2500 BCE. The Indus Valley civilisation stretched up to large parts of Afghanistan in the north. Alexander the Great and his Macedonian army arrived at what is now Afghanistan in 330 BCE after the fall of the Achaemenid Empire during the Battle of G