The title of this thesis includes three key words: evolution (reasons and consequences), tba 'Tunisian (name of the musical mode) and first half of the twentieth century (colonial era characterized by socio-cultural upheavals in Tunisia, as in the Arab world) . The first part entitled Tunisian classical music includes on the one hand, the presentation and the formal and rhythmic analysis of the Tunisian maluf, in particular the most important of its profane forms, namely the nawba and the most important ritual musical manifestations ( 'al-'isawiya and' as-sulamiya), on the other hand, a discussion around terminological problems and, thirdly, a comparative study of Maghrebian music of Andalusian origin which leads to explanations about the reasons (cosmic, spiritual and metaphysical) which are at the origin of the name of the musical mode Maghrebin tba '.
The second part, entitled from master to disciple, reviews, after a biographical introduction and musical analysis of works considered interesting, the contribution of each composer, chosen according to the tubu 'of the first half of this century . Finally, the third part, titled tba 'in Tunisian musical writing of the twentieth century, begins with a presentation recapitulating the different epochs of the history of Tunisia that made the tubu', in this country include components of different origins (Mediterranean).
Then, in order to expand the results of our analyzes (modal, acoustic and stylistic), we proceeded to the comparative study of tubu 'and maqamat before reviewing the composition of the Tunisian musical modes and their evolutions in the first one. half of the twentieth century. Finally, we have found it useful to show that Arab fashions have inherited a great deal from Greek fashions. This can lead to a new evolution of Arabic musical writing.