The tribal area of Pakistan's northwest is home to tens of thousands of Afghans of the Pashtun ethnic group - the same ethnic group as the Taleban.
The Pakistani intelligence service sponsored the Taleban movement, providing funding, weapons and logistical support. Much of the trade in drugs and weapons went through the region.
Peshawar, in the heart of the region, lies an eight-hour drive from the Afghan capital Kabul, across the Khyber Pass. It was the headquarters of al-Qaeda between 1989 and 1991, according to the US indictment against Zacarias Moussaoui.
Many of the al-Qaeda and Taleban fighters who escaped from the US onslaught are thought to have found refuge in this region. Abu Zubaydah, described as one of Osama Bin Ladenís inner circle was arrested in Pakistan in March.
Pakistan blames al-Qaeda for a spate of bombings and the murder of American journalist Daniel Pearl. Its security forces continue to pursue, seize and shoot al-Qaeda fighters.