The Durand Line was established in 1893 as the international border between the Emirate of Afghanistan and the British Indian Empire by Mortimer Durand, a British diplomat of the Indian Civil Service, and Abdur Rahman Khan, the Emir of Afghanistan, to fix the limit of their respective spheres of influence and improve diplomatic relations and trade.

The Durand line cuts through to demarcate Khyber Pakhtunkhwa, Balochistan, and the contested region of Gilgit-Baltistan of northern and western Pakistan from the northeastern and southern provinces of Afghanistan.

[15][16][17][18][19] In 2017, amid cross-border tensions, former Afghan President Hamid Karzai said that Afghanistan will "never recognise" the Durand Line as the border between the two countries.

[24] The Pashtun area (known today as the "Pashtunistan" region) fell within the Ghaznavid Empire in the 10th century followed by the Ghurids, Timurids, Mughals, Hotakis, by the Durranis, and thereafter the Sikhs.

In 1893, Mortimer Durand was dispatched to Kabul by the Government of India to sign an agreement with Amir Abdur Rahman Khan for fixing the limits of their respective spheres of influence as well as improving diplomatic relations and trade.

[2] The two parties later camped at Parachinar, a small town near Khost in Afghanistan, which is now part of the Federally Administered Tribal Areas (FATA) of Pakistan, to delineate the frontier.

Detailed topographic maps locating hundreds of boundary demarcation pillars were soon published and are available in the Survey of India collection at the British Library.

[27][28] In 1896, the long stretch from the Kabul River to China, including the Wakhan Corridor, was declared demarcated by virtue of its continuous, distinct watershed ridgeline, leaving only the section near the Khyber Pass to be finally demarcated in the treaty of 22 November 1921, signed by Mahmud Tarzi, "Chief of the Afghan Government for the conclusion of the treaty" and "Henry R. C. Dobbs, Envoy Extraordinary and Chief of the British Mission to Kabul.

Concurrently, Afridi tribesmen began rising up in arms against the British, creating a zone of instability between Peshawar and the Durand Line.

[33] Pakistan believes, and international convention under uti possidetis juris supports, the position that it should not require an agreement to set the boundary;[31] courts in several countries around the world and the Vienna Convention have universally upheld via uti possidetis juris that binding bilateral agreements are "passed down" to successor states.

Twelve Afghan provinces are located along the border: Nimroz, Helmand, Kandahar, Zabul, Paktika, Khost, Paktia, Logar, Nangarhar, Kunar, Nuristan and Badakhshan.

The two countries are major trade partners, and therefore the various border crossings are economically important for the wider region,[41] particularly the Torkham and Khyber Pass that is also the main land connection between Central Asia and the Indian subcontinent.

During Operation Cyclone, the ISI, with support and funding from the Central Intelligence Agency (CIA) of the United States, recruited mujahideen militant groups on the Pakistani side of the Durand line to cross into Afghanistan's territory for missions to topple the Soviet-backed Afghan government.

[42] Afghanistan KHAD was one of two secret service agencies believed to have been conducting bombings in parts of the North West Frontier (now Khyber Pakhtunkhwa) during the early 1980s.

[43] U.S State Department blamed WAD (a KGB-created Afghan secret intelligence agency) for terrorist bombings in Pakistan's cities in 1987 and 1988.

[33]Because the Durand Line divides the Pashtun and Baloch people, it continues to be a source of tension between the governments of Pakistan and Afghanistan.

[52] In August 2007, Pakistani politician and the leader of Jamiat Ulema-e-Islam, Fazal-ur-Rehman, urged Afghanistan to recognise the Durand Line.

[53] Press statements from 2005 to 2007 by former Pakistani President Musharraf calling for the building of a fence on the Durand Line have been met with resistance from numerous Pashtun political parties in Afghanistan.

[11]Aimal Faizi, spokesman for the Afghan President, stated in October 2012 that the Durand Line is "an issue of historical importance for Afghanistan.

The Afghan government claimed that the Pakistani military established bases up to 600 meters inside Afghanistan in the Yaqubi area near bordering Mohmand District.

[59] In 2007, Pakistan erected fences and posts a few hundred metres inside Afghanistan near the border-straddling bazaar of Angoor Ada in South Waziristan, but the Afghan National Army quickly removed them and began shelling Pakistani positions.

[58] Leaders in Pakistan said the fencing was a way to prevent Taliban militants from crossing over between the two nations, but Afghan President Hamid Karzai believed that it is Islamabad's plan to permanently separate the Pashtun tribes.

[63] Many forms of illegal activities take place, such as smuggling of weapons, narcotics, lumber, copper, gemstones, marble, vehicles, and electronic products, as well as ordinary consumer goods.

At the same time, the United States is reviewing the Reconstruction Opportunity Zones (ROZ) Act in Washington, D.C., which is supposed to help the economic status of the Pashtun and Baloch tribes by providing jobs to a large number of the population on both sides of the Durand Line border.

In June 2011 the United States installed a biometric system at the border crossing near Spin Boldak, aimed at improving the security situation and blocking the infiltration of insurgents into southern Afghanistan.

[74] I'm speculating, but natural possibilities include a signal to Karzai and to (the United States) that we can't push Pakistan too hard.

[75] In response to that incident, Pakistan decided to cut off all NATO supply lines as well as boost border security by installing anti-aircraft guns and radars to monitor air activity.

[85] On 20 March, Pakistani Prime Minister Nawaz Sharif ordered the reopening of Afghanistan–Pakistan border as a "goodwill gesture", 32 days after it was closed.

[89] An Afghan diplomat at the World Trade Organization (WTO) claimed that Afghanistan suffered a loss of 90 million U.S. dollars as a result of closure of border by Pakistan.

[91] Pakistan has been constructing a border barrier since 2017 to prevent terrorism, drug trafficking, refugees, illegal immigration, smuggling and infiltration across the Durand Line.