Please note Uzbeks make up 9% of the population, making then the 3rd or 4th largest group in Afghanistan, tied with the Hazara at 9% (i.e. The Uzbeks and Hazara are both about 9% so one is the 3rd largest and the other is the 4th largest) but behind the 42% of the population for the Pasthuns (Other report 50%) and 27% Tajiks (Other report 22%, they seems to be an attempt to max the number of Tajiks and Uzbeks while minimizing the number of Pasthuns and Hazaras).
Now the Hazara, who make up about 9% of the population, this tribe is the largest Shiite Moslem group in Afghanistan, conquered in the late 1800s by the Pasthuns and discriminated afterward for being non-Pasthuns AND Shiites. During the war with the Soviet Union become the single most united group in Afghanistan, but also the group most allied with Iran, thus opposing BOTH the Taliban (Pasthun dominated) and the Northern Alliance (Tajik and Uzbek dominated):
http://countrystudies.us/afghanistan/38.htmAfter the Pasthuns, Tajiks and Hazaras come the Aimak at 4% of the population. The Aimaks are a Tajiks people that over time have separated completely from the rest of the Tajiks and as such have an independent tribal system.
Next come the Turkmen population at about 3% of the population. The Turkmens are related to the Turkmen of Turkmenistan (Both speak a variation of Turkish spoken by Turks in Turkey but the Turks in Turkey and the Turkmen in Turkmenistan have been separated by Iran since at least the 12th century, through that was NEVER a complete break). Just a comment that the Turkmen and Turks are separated groups at the present time, unlike the Turkmen of Afghanistan who tend to be related to the Turkmen of Turkmenistan.
The Baloch make up about 2 % of the population of Afghanistan. The Baloch tend to be in Southern Afghanistan north of Baluchistan which is part of Southern Pakistan. They connection is with tribal members in Baluchistan NOT with the test of Afghanistan.
The rest of the population of Afghanistan is about 4% of the populations made up of various minor tribes all independent of each other AND isolated from each other by the various mountains of Afghanistan. While small in population and isolated, they have very strong tribal ties but of a local nature as oppose to anything that crosses any regional border.
Just comment that when you are dealing with the population of Afghanistan you are NOT dealing with anyone who sees himself or herself as an "Afghan" but someone tied in with some other group, a local tribe as seen in the Aimaks and Hazara, a more regional tribe as seen in the Pasthuns, or groups who see themselves as belonging to a larger, but foreign group such as the Turkmen, Uzbeks, Tajiks, Balochs, Kyrgyzs, and the Kazakhs, all of which have large populations outside of Afghanistan from which they can get support (The Kazakhs and Kyrgyzs, both have a very small number of people in Afghanistan, these are two people that make up the 4% "other tribes", but some Kazakhs exist inside Afghanistan).