As previously mentioned, the first four strings represented spiritual directions within society and the culture. They “symbolized the elements, the phases of the moon, the directions, the seasons, the weeks of a month, the divisions of a day, of a body, of human life, and the four humors – that is, in descending order, the yellow bile, the blood, the phlegm, and the black bile, (Sachs, 1940: p. 253).” When this Ziryab character added a fifth pair of strings, he was stirring up the colloquial pot a bit. But according to Hickmann, Ziryab said that the four strings were called yellow, red, white and black for the human emotions, and that one had forgotten the soul, and that the soul lives in the blood. For this reason, the 5th string of Ziryab is also colored red. (Hickmann, 1970: p. 23)

Ziryab, who was a freed slave, carried the ‘ud as it existed in Iraq, and the Iraqi method of playing all the way with him to Moorish Spain, on the banks of the Guadalquivir, at the far reaches of the empire. When he arrived there, the cities of Cordoba, Seville, and Granada were centers of cultural, artistic and religious activity. These centers had a huge impact on medieval Europe. Ziryab introduced the concepts of a new music, pulled out of Greek, Persian and Arab music, that would deeply influence the beginnings of European classical music. Pictured here is a picture of an ivory carving from 968, in which there is a standing ‘ud player with a plectrum. (http://www.kairarecords.com/oudpage/Oud.htm)

(http://www.vanedwards.co.uk/history1.htm)

The lute became a popular instrument in Europe…. (http://www.vanedwards.co.uk/history1.htm)
The introduction of lutes into Europe inspired a slow spreading of the lute to all corners of the continent, and by the 14th century, the lute was widespread and well-known. The earliest existing manuscript detailing the plans for building a lute in Europe is from about 1440 by Henri Arnaut de Zwolle, (http://www.vanedwards.co.uk/history1.htm).
The Arabic ‘ud is still played using a plectrum, and was also in Europe until the 15th century, when finger-style playing started gaining popularity. The melodic and polyphonic playing of the Arab style using the plectrum became obsolete as the finger-style playing led to more and more harmonies with several voices at once. Harmony was developing. http://www.vanedwards.co.uk/history1.htm

And now, several hundred years later, the ‘ud still exists in much the same form that it had in Persia and Iraq, or perhaps, the form it had taken by the time it was brought to Moorish Spain. The lute, however, evolved and changed into many other forms of instruments over the hundreds of years in Europe, developing into the guitar, the mandolin and dozens of other instruments, though giving up its status of ‘prince of all instruments’ to the organ, piano, and now, electronics and electric instruments.

The ‘ud is still the backbone of Arabic music, especially during the revival of the last two hundred years in the middle east. Bill Bradley said:
… the oud is probably pretty much unaltered since that time—a striking contrast to the lute or guitar. The oud appears to have gone into something of a decline in the 16th century, enjoying a huge resurgence in popularity in the 19th and 20th centuries. This resurgence was bound up with the rising sense of Arab identity in modern times. (http://userpage.fu-berlin.de/~telehist/ambass/ud.htm)

Bradley went on to talk about the cultural conference in Cairo in 1932 when the quarter tones became fixed. Though there is still much freedom in the singing and playing of the Arabs, there was ‘a certain loss of fluidity’. “Nowadays electric organs for sale in the Arabic world can be programmed with quarter tones.” (http://userpage.fu-berlin.de/~telehist/ambass/ud.htm)