Some information from Wikipedia:
Rubab or robab is a lute-like musical instrument originally from Afghanistan but is also played in the neighbouring countries, especially Pakistan. It derives its name from the Arab rebab which means "played with a bow" but the Central Asian instrument is plucked, and is distinctly different in construction. The rubab is mainly used by Tajik, Pashtun, Kashmiri and Iranian Kurdish classical musicians.
The rubab is a short-necked lute whose body is carved out of a single piece of wood, with a membrane, covering the hollow bowl of the sound-chamber, upon which the bridge is positioned. It has three melody strings tuned in fourths, three drone strings and 11 or 12 sympathetic strings. The instrument is made from the trunk of a mulberry tree, the head from an animal skin such as a goat skin, and the strings either gut (from the intestines of young goats, brought to the size of thread) or nylon.
The rubab is attested from the 7th century CE. It is mentioned in old Persian books, and many Sufi poets mention it in their poems. It is the traditional instrument of Khorasan.
In Tajikistan a similar but somewhat distinct rubab-i-pamir (Pamiri rubab) is played, having a shallower body and neck. The rubab of the Pamir area has six gut strings, one of which, rather than running from the head to the bridge, is attached partway down the neck, similar to the fifth string of the American banjo.
Example of playing: