Rabāb used to be a term for any stringed instrument.
rabāb or rabābah, an Arabic fiddle in the 10th century. Parent of the medieval European rebec or rubebe (11th-18th century Mediterranean/Balkans) and lira (like the lyre?) The ancient rabāb was the ancestor of almost all European bowed instruments. It had a membranous belly, 2-3 strings, and narrow neck. Its range was about an octave.
Large rebab, more range than the ancient rabab. (similar instrument - kamanche or khomanche) Iraqi and Bedouin - joza, variant with coconut-shell soundbox.
Central and East Asia
The more western, the higher pitched the instrument (?).
Huqin (instrument family) - Chinese variant
Morin khuur - in Mongolia
Kyrgyztan - kobyz
Mughal Empire The seni rabab - wood body with resonator and six strings, no frets and traditionally no sympathetic strings.
Kabuli rabab (Afghan) - hollow wood body with gut or nylon strings.
Rebab is a component of gamelan, as a bowed two-stringed lute made of wood or coconut shell covered with hide. Usually two per gamelan ensemble. Sometimes used in healing rituals.
== Notes ==
Rabab - original ancestor.
Rebab - used in gamelan, general name for r*bab in most resources.
Robab or rubab - originated in Afghanistan. (Britannica 1911: The pear-shaped instrument...with strings plucked by the fingers, — the lute of the 6th century A.D., — is seen first on a frieze from Afghanistan.) Possibly diverged from here. Short-necked lute with three melody and 2-3 drone strings, usually nylon.
https://www.metmuseum.org/toah/works-of-art/89.4.403/ (Algerian rebab)
https://www.wdl.org/en/item/10826/ (Central Asian rebab, c. 1880)
http://collections.nmmusd.org/Gamelan/9870/Rebab9870.html (Javanese rebab, used in gamelan)
https://research.britishmuseum.org/research/collection_online/collection_object_details.aspx?objectId=3439763&partId=1 (Central Asian rabob, Xanthus)