To quote Kyriakos Kalaitzidis, the Oud is used “all over the Near and Middle East…by the Persians, the Armenians, the Greeks, the Jews, and across the Arab and Islamic world”. Its original form was different to the contemporary version. Historically, it played a leading role in shaping the musical culture of the Arab world. String instruments were introduced into the Arab world by the Persians and Byzantines, after the expansion of Islam. It is likely that the Oud, or one of its predecessors, was among them. The Arabs later named it Al Oud, which translates as “wood” or “flexible rod”. The Arabs, led by Ibrahim, Ziryah and Farabi, developed an entire system of musical theory for the Oud, based upon the texts of ancient Greek theorists. In the past, in fact, Arab composers used the Oud exclusively in their compositions. After the Arab occupation of Spain (8th-15th century A.D.), the musical culture connected to the Oud contributed to the development of the musical traditions of Andalusian gypsies. It is a solo instrument, ideal for improvisation and vocal accompaniment. The Oud consists of a large, pear-shaped body and a short but wide neck, without frets (which divide the neck into segments that correspond to semitones). The shape and size of the instrument varies from place to place. Its body is small in Egypt, Syria and other Arab states, and even smaller in Turkey, while in Iraq the holes on the soundboard are open, without decorative rosettes. The Oud originally had two strings, then four, and the contemporary version now has five or six. The Lebanese musician Farahat Hashem built an instrument with seven strings, which reached both the low and high range of scales. In the past, the strings were made of animal intestines, and the pick or plectrum out of cherry wood or animal horns. Nowadays, both the strings and plectrums are made of plastic. The Oud is known in almost every part of the world. Since the 9th century, it has played a major part in the development of the both the practices and theory of Mediterranean musical traditions. The Oud is one of the key instruments of the Middle East, upon which the musical scales known as maqam were developed. Each maqam consists of a tetrachord and a pentachord, which are played alternately. Maqam exist in many variations, and across a number of countries.