It is related to the Iraqi instrument the djose, which has four strings. The introduction of the rebab into Western Europe has possibly coincided with the conquest of Spain by the Moors, in the Iberian Peninsula. There is however evidence of the existence of bowed instruments in the 9th century also in Eastern Europe: the Persian geographer of the 9th century Ibn Khurradadhbih cited the bowed Byzantine lira (or lūrā) as typical bowed instrument of the Byzantines and equivalent to the Arab rabāb. The rebab is used in a wide variety of musical ensembles and genres, corresponding with its wide distribution, and is built and played somewhat differently in different areas. In Southeast Asia, the rebab is a large instrument with a range similar to the viola da gamba, whereas versions of the instrument further west tend to be smaller and higher-pitched. The body varies from being ornately carved, as in Java, to simpler models such as the 2-string Egyptian "fiddle of the Nile" may have a body made of half a coconut shell. The more sophisticated versions have a wooden soundbox and the front may be half-covered with beaten copper, and half with goatskin.
Enjoy the music of this great instrument
About the rabab(continued):
Rabab is a very ancient instrument found primarily in Afghanistan but in India is common in Kashmir. It is a hollowed-out body of wood with a membrane stretched over the opening. Combinations of gut (or nylon) and metal strings pass over a bridge which rests on a taught membrane. The rabab is mentioned quite frequently in old texts. However this is usually the seni rabab which is different from what we think of today. It is common to refer to the modern rabab as the kabuli rabab to distinguish it from the seni rabab.
Although the kabuli rabab is the style that is normally thought of today, over the centuries the term has been applied to a variety of instruments. Therefore as a generic term it has been applied to a variety of instruments that even impinge upon the sarod and the sarangi.
There is evidence that this instrument may be the progenitor of a number of Indian instruments. The saringda, sarod, and the sarangi are the ones most commonly attributed to this instrument. At first it may seem hard to make the connection between a plucked instrument and a bowed instrument, however notice the "waist" in the middle of the rabab. This is an indication that the instrument at some time was played with a bow. All bowed instruments must be narrow at the place where the bow must pass.