The UN has urged Afghanistan's neighbours to keep their borders open as the number of civilians fleeing the Taliban onslaught swells.
Thousands of those internally displaced have been arriving in Kabul, seeing the capital as their last safe refuge.
On Friday, the Taliban seized the country's second-largest city Kandahar, the latest provincial capital to fall.
The southern city of 600,000 people was once the Taliban's stronghold, and is strategically important because of its international airport, agricultural and industrial output.
The insurgents also took the nearby city of Lashkar Gah, and now control about a third of Afghanistan's provincial capitals.
The advance comes as US and other foreign troops withdraw after 20 years of military operations. More than 1,000 civilians were killed in Afghanistan in the past month alone, according to the UN.
Sahraa Karimi, an Afghan filmmaker in Kabul, told the BBC it felt like the world had turned its back on Afghanistan and she feared a return to "dark times".
Life under the Taliban in the 1990s saw women forced to wear the all-covering burka, education restricted for girls over 10 and brutal punishments brought in, including public executions.
"I am in danger - [but] I don't anymore think about myself," Ms Karimi said. "I think about our country... I think about our generation: that we did a lot to bring these changes.
"I think about young girls... there are thousands of beautiful, young talented women in this country."