The most important structural element of malouf, however, is the Andalusi nuba, a two-part suite in a single maqam (an Arab mode organized by quarter-tones), which lasts about an hour. A nuba is a musical form introduced to North Africa with the migration of Muslim inhabitants of Spain in the 13 and 14th Century. It is divided to many parts :Isstifta7 Msader which are instrumental pieces Then come Attouq and the Silsla which introduce to the poems. The sung pieces begin with the Btaihia: A set of poem composed on the Main mode of the Nuba (There are several Modes in Tunisian Music Thaiil raml Sikah tounssia Ispahan Isbaaïn) on a heavily syncopated rhythm called BtaiHi. Then come al barawil, Al khfeiif Al Akhtam which close the nuba. The rhythms grow fast from a component to anthem of the Nuba. Each component of a Nouba has its specific rhythm which are the same in all the 13 Nouba known today.