The modern nation-state of Afghanistan was mapped by British bureaucrats at the end of the nineteenth century as a way of keeping their Empire from touching the Russian Empire, so as to avoid superpower conflicts. This kept Afghanistan neutral and uncolonized, but with arbitrary borders. Physically, the country presents a huge mountainous spine surrounded by areas of desert and steppe, open on all sides to neighboring lands: Pakistan, Iran, and the Central Asian countries of Turkmenistan, Uzbekistan, and Tajikistan, with a tiny Chinese border in the Wakhan panhandle of the northeast.
The ethnographic maps show how most of the populations of Afghanistan overlap with their cousins across the national boundary. Only a few groups live purely in Afghanistan, mainly the Hazaras of the central region and some small peoples of the northeast. No one knows the population sizes; figures are all estimates. At the time of my research, this underpopulated nation officially had 12 million people, but there were probably far fewer on the ground.
The largest ethnic group is the Pashtuns, who speak an Iranian language, related to Persian, the language of the next largest group, the Tajiks. Their Persian, called Dari, is a regional variant of the language spoken in Iran (Farsi) and Tajikistan (Tajik). Uzbeks, Turkmens, and the smaller populations of Kazakhs and Kirghiz speak languages of the Turkic family. Some two dozen languages were circulating in Afghanistan, some limited to a couple of mountain valleys. You will notice how the ethnographic maps list different ethnic groups, sometimes classifying people by language, sometimes by "ethnicity," whatever that might be in a land where people strategically defined themselves through marriage alliance and local loyalties. They live at close range and accommodated to each other's patterns in small-scale, daily-life ways. All ethnic issues are complex and often hard to define in this country, where "identity" starts out with extended family and qowm, a hard-to-pin-down word that specifies the smallest unit of loyalty in a set of concentric circles of affiliation.
I worked in the North, where the Pashtuns were a distinct minority, with Uzbeks and Tajiks being dominant alongside Turkmens. The Tajiks were there first, as part of a settled, agricultural Iranian population many centuries old. Tajik is a general word for several types of Dari-speakers in Afghanistan. The Uzbeks arrived around 1500 from Central Asia, farther north, and adjusted to Tajik culture, moving from their nomadic ways to village life, though traces of seminomadic life lingered among several small populations of the North. Together, the Uzbeks and Tajiks formed a kind of joint culture that set the tone for other groups. Some groups came in the twentieth century, escaping the expansion of Soviet power in the 1920s and 1930s, bringing their flocks with them, in the case of the Turkmens, famous for their karakul sheep and carpet-weaving. The Kazakhs, in small urban enclaves, and the Kirghiz, isolated at 20,000 feet in the Wakhan panhandle, are in this category.
Other small populations included Hazaras from central Afghanistan, and enigmatic groups with names like Arab (though not middle eastern Arabs), Moghol (though not Mongols), and several others. Each ethnicity also has distinct subgroups.