After the Soviet withdrawal they quickly extended their influence and burst onto the scene as an armed Islamic group in Afghanistan in mid-1994.
They restored order amid a fierce civil war from 1992-1996, capturing the ethnic Pashtun southern city of Kandahar in October 1994 and Kabul on September 26, 1996 - with backing from Pakistan and the tacit approval of the United States.
But since their ousting in 2001 they have waged a ferocious insurgency against the Western-backed Kabul government that has claimed tens of thousands of lives.
Pakistan denounces US strike believed to have killed Afghan Taliban chief
Mansoor ran the group for more than two years following the unannounced death from illness in 2013 of Taliban founder Mullah Omar.
He officially became leader last July after Afghan officials disclosed Omar's death.
Following the announcement of Mansoor's death, members of the Taliban's Shura, or high council, began meeting at an undisclosed location to choose his successor.
The Taliban heartland is southeast Afghanistan, a region dominated by Pashtun tribes. The movement links many different groups, notably the Haqqani network of Sirajuddin Haqqani that is based in Waziristan, a border region in northwest Pakistan.
After their takeover of Kabul in 1996 the Taliban enforced an ultra-strict version of Sharia or Islamic law, with games, music, photos, cinema and television forbidden and girls over the age of 10 barred from attending school.
In March 2001 they destroyed the famous Bamiyan Buddha statues in central Afghanistan, provoking outrage around the world.
Iran denies Mullah Mansour crossed Iran’s border to enter Pakistan
Women had to wear full-length burqas and men were required to grow beards. Strict punishments including public executions were enforced.
The Taliban controlled almost all of Afghanistan and turned it into a sanctuary for fighters training for holy war - notably al Qaeda leader Osama bin Laden.
The Taliban refusal to surrender bin Laden after the 9/11 attacks in the United States prompted a US-led invasion.
The Taliban regime capitulated on December 6, 2001 and its leaders fled to mountainous tribal areas on both sides of the border with Pakistan to rebuild and hit back at the "crusaders".
They mounted countless attacks on US-dominated NATO troops in Afghanistan and on local forces loyal to Hamid Karzai - a Pashtun who became the country's first democratically elected president in October 2004 but who was scorned by the Taliban as a US puppet.
Karzai handed power to Ashraf Ghani in 2014, but Taliban attacks have continued and even grown fiercer, especially since NATO ended its combat mission in December 2014 and withdrew the bulk of its forces.
Man believed to be Taliban leader had returned from Iran
A training and special operations cadre of around 13,000 soldiers remains, of whom roughly 10,000 are supplied by the US.
But almost all the frontline ground fighting is now done by Afghan troops or police, who have sustained thousands of deaths or injuries.
Taliban attacks intensified under Mansoor.
Last September they briefly captured the strategic northern city of Kunduz, their most spectacular victory in 14 years.
The southern opium-rich province of Helmand is almost entirely under insurgent control.
The militants also staged several deadly raids in the heart of Kabul, responding to increased pressure from the Islamic State group which has become a rival for militant leadership.
In July 2015 Pakistan hosted direct talks between Afghan and Taliban leaders, with support from China and the US, but they collapsed after Mullah Omar's death was revealed.
The drone attack came just days after representatives from the US, China, Pakistan and Afghanistan held another round of negotiations in Islamabad aimed at reviving those direct talks.
But Mansoor, whose death was confirmed Monday by President Barack Obama, was seen by Washington as an obstacle to peace.
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