In July, US President Joe Biden announced that American troops would complete a total withdrawal from Afghanistan by 31 August.
But who are the Taliban and why are they so feared?
Watch: 'We will burn your house' – Taliban hunt former UK staff unable to escape Afghanistan.
Who are the Taliban?
The group came to prominence in Afghanistan during the early 1990s, after the withdrawal of Soviet troops from the country, and governed in the country from 1996 to 2001.
It is believed they emerged from religious seminaries, largely financed by money from Saudi Arabia, which preached a strict form of Sunni Islam.
The Taliban, meaning 'students' in the Pashto language, promised to restore peace and security in Pashtun areas of Pakistan and Afghanistan by enforcing their own version of Sharia law.
Contrary to popular belief, there is not one single 'Taliban', but several different groups.
The largest and most effective in Pakistan are the TTP – the group that attempted to murder Malala Yousafzai for going to school under Taliban rule.
Afghanistan and Pakistani Taliban are rivals as well as allies as they have slightly conflicting ideologies – leading to clashes in the past.
Pakistan was one of only three countries to recognise the Taliban when they were in power in Afghanistan, and the last to sever diplomatic ties with the group.
Saudi Arabia and the United Arab Emirates (UAE) also recognised the Taliban.
Watch: Ex-military chiefs voice concern over Afghanistan amid Taliban gains.
What do the Taliban believe?
The group implements an extremely strict version of Sharia Law, Islam's legal system which stems from both the Koran and fatwas – rulings of Islamic scholars.
Females over the age of 10 were banned from receiving an education while the Taliban governed Afghanistan, with television, music, cinema and social media also banned.
Men were required to grow beards and women were told to wear the burka.
Why is the group feared?
The Taliban have been accused of several human rights abuses and enforce strict punishments for crimes.
This can include amputations and public executions.