What boundary line separates Afghanistan and Pakistan?

The Durand Line is the boundary line separating Afghanistan and Pakistan.

The line was established in 1893 through an agreement between Mortimer Durand, a British diplomat, and Abdur Rahman Khan, the emir of Afghanistan. It defined the boundary between Afghanistan and the British Indian Empire, largely by marking their respective spheres of influence. After the partition of British India in 1947, Pakistan inherited the boundary.

The border is roughly 2,640 kilometres long and runs through rugged mountain terrain, including areas around the Khyber Pass. It also cuts across communities with shared Pashtun and Baloch identities, which has made the frontier politically sensitive and difficult to police.

Pakistan treats the Durand Line as its international boundary with Afghanistan, while successive Afghan governments have disputed or refused to recognize it as a permanent international border. That disagreement explains why the line is both a formal boundary and a continuing geopolitical controversy.

The other options refer to different boundaries. The Radcliffe Line divided British India into India and Pakistan in 1947, the McMahon Line concerns the India–China frontier, and the Blue Line is used for other regional boundaries.