From the 8th century, one of the main music centers of the Arabic nation besides the key places Damascus and Baghdad, was Spain. When Arabs began to expand in southern Spain, first below the rule of Almoravids and later below the Almohads, two different cultures "crashed" themselves, and then the fusion developed in a variety of cultural issues. Regarding music, this fusion was known as Andalusian or Moorish branch of Islamic music. Zaryab was the main figure of this development. A gifted student of Ishaq al-Mawsili, had to migrate from Baghdad to Spain because he got advantage over his teacher (a severe offense, then and nowadays). Settled in the court of Cordoba he was an amazing singer, created a famous school of music, and made one of the main changes on ouds: to add a fifth (G) bass string. Regarding music theory, he rearranged it completely, setting free the metrical and rhythmical parameters and creating new ways of expression (mwashah, zajal, and nawbah -suite-)