This research aims to express the changing process that happened in Mandar as a result of Dutch colonial intervention. From this, it can be seen the early structure that made by Mandar people, their custom and behavior; and finally to bring a new structure that come from their interaction with colonial power. From the period as temporal term, source of information is explored from a past data, especially from colonial archives. Some articles from journals and newspapers, as a contemporary mass media, contribute much information for reconstruction. The structure that made by Mandar people in 18th and 19th century was identified with a maritime piracy. By a reason to end this criminality, Dutch colonial government took a drastic measure with sending her military expedition to punish Mandar people. The expedition motivated the Mandar War in 1868-1869, and ended with a political contract between Mandar and Dutch in 1870. As a conclusion, Mandar is proven to have a difference structure with other political units in South Sulawesi. The structure is consisted of two: power system that composed by seven kings or “maradia”; and diaspora system that spread as long coast of Sulawesi. The contract, that forced by Dutch, could not end the both structures, even though the Dutch regarded that she could establish her political domination.