A lot of efforts, particularly in seismics have been dedicated to study of extensional margins. Based on a comparative study of several narrow basins of SE Asia, with emphasis on the South China Sea, we explore parameters which are important in the early processes of rifting. These include the lateral variations in rifting style and the discrepancies in the timing of the breakup unconformity. The response of the crust to the stretching is very sensitive to inherited crustal nature. In former active margin the presence of large granitic bodies and intra-crustal discontinuities with weak rheology appears to be common characteristics which condition the location of detachments connected to rifting faults. The extension history goes through several stages, including an early diffuse event and a late more localized one. The specific locations of the latter are the locus of inversion tectonics which has been for decades the target structures in oil exploration.