Panjshir, the last Afghan province to fall to the Taliban

The Taliban claimed victory on Monday over opposition forces in Panjshir province, completing their takeover of the country following the stunning capture of Kabul last month and the chaotic withdrawal of foreign troops.

Here are some key facts about Panjshir, and the battle for the valley:

Where is Panjshir?

Located just north of the capital Kabul, Panjshir is one of the smallest of Afghanistan's 34 provinces.

It is of strategic importance, providing the main route out of Kabul to the north where important cities like Mazar-i-Sharif and Kunduz are located.

It is populated largely by ethnic Tajiks, a sizeable minority group in Afghanistan. The Taliban are mainly drawn from the largest ethnic Pashtun group.

The region's mountainous, rugged terrain and deep central valley give defenders a significant advantage, forcing attackers to traverse steep mountain passes or enter through the mouth of the valley, where they have to face off against foes commanding higher ground.

What is the region's recent history?

Panjshir was a critical province in the resistance against the Soviet occupation in the 1980s. The burned out shells of Soviet tanks and armoured personnel carriers still litter the valley and river beds, testament to the fierce fighting during the occupation.

It was also the centre of resistance against the Taliban when it ruled Afghanistan from to 1996 to 2001.

Key to those holdouts was Ahmad Shah Massoud, a militia leader known as the "Lion of Panjshir". He was assassinated by al Qaeda in a suicide bombing two days before the September 11 attacks in 2001.

His Northern Alliance ousted the Taliban with heavy US air support two months after his death.

What happened after Kabul fell?

Following the withdrawal of almost all remaining US and other Western troops in July, the Taliban's conquest of Afghanistan gathered pace, ending with the fall of Kabul on Aug. 15.

After the capital's collapse, thousands of former Afghan army and special forces soldiers massed in Panjshir, joining local militia groups under the leadership of Massoud's son, Ahmad Massoud, and former Afghan vice president Amrullah Saleh.

Armed with weapons including helicopters, they held out against the Taliban, refusing to surrender, although Massoud called for peace talks with the aim of winning autonomy for Panjshir.

Those talks led to nothing, with each side blaming the other for their failure, and days of clashes led to heavy casualties on both sides.

After the Taliban claimed it had captured Panjshir, Massoud tweeted to say he was safe, without revealing his location. Saleh's whereabouts are also unknown.

What happens next?

The capture of Panjshir would be a significant achievement for the Taliban, who have never been able to hold the valley. But it is not yet clear how much of the province they control.

While the group posted photos of its fighters standing in front of the provincial governor's compound, much of the province is composed of smaller, remote mountain valleys that provide areas for opposition forces to regroup.

However, Massoud's father drew much of his power through access to Tajikistan via Takhar province, which he also controlled. That is now in the hands of the Taliban, making resupplying any remaining opposition fighters more difficult.