The southwest Asian landmass consisting of Afghanistan and Pakistan entails a complex geodemographic configuration. The cross-border linkages between the two countries are reinforced by the fact that the Pashtun ethnic group resides on both sides of the border. In Pakistan, the Pashtuns constitute the second-largest ethnic group — about 15 percent of the population — and are located in the northwestern border regions, whereas in Afghanistan the Pashtuns form the largest ethnic group at 42 percent. The Pashtuns in Afghanistan are concentrated in the country's east and south and struggle for power with the minorities: Tajiks, Hazaras, Uzbeks and others. In contrast, the Pashtuns in Pakistan largely inhabit the peripheral mountainous regions in the northwest and have historically posed a challenge to national integration for the country's Punjabi-Sindhi core. Afghanistan's demographic distribution coupled with a difficult geography poses serious challenges for any form of central rule. As far as Pakistan is concerned, its Pashtun population is a means of not just securing the core, but is also a medium through which the Pakistani state can project power into Afghanistan.
