The U.S.-led war in Afghanistan formally ended in 2014, but there are still nearly 13,000 NATO troops in the country, representing 42 countries.
This recent conflict is just a blip on the timeline of foreign involvement in Afghanistan. It has been the scene of military campaigns dating back centuries, featuring Alexander the Great, Mongols, Muslim Arabs, the British, the Soviet Union and now NATO.
The BBC's Dawood Azami joins Here & Now host Jeremy Hobson with details on this history.
This segment aired on January 20, 2016.