The introduction and spread of Islam in South East Asia is an entry point for Islamisation of Nusantara history, but it has been the most probelmatic and unclear. In spite of that, there are some theories come up and set up the debates and polemic which have never be`the end. This article aims to break down the discources of the Islamisation of Nusantara, especially about the introduction and spread of Islam in South East Asia. Based on the prior library research with the cuallitatif approach methodology, this article examines five of those theories, namely are Indian, Arabian, Persian, Chinesee, and accomodative theories. Actually, those theories are arguments to answer three core problem, namely the origin place of Islam in South East Asia, the actors who came with, and the time of it's introduction. The debates of those theories will never be`the end becouse of the lack of data and the patisan interest to some core problems while ignore the other ones. This article not only explains theories of accommodation as sintesys, but also describes some factors and channels of Islamisation that has constructed some characteristics of Shoth East Asian Islam. These arguments are used to place the position of South East Asia Islam or Nusantara Islam as a Islamic cultural spheres that distinctive and equals to the others in the Muslim World.