The concept of “Indosinian” was first introduced by Fromaget (1931, 1934) for folding in Indochina that took place during the Anthracolithic (a term, no longer commonly in use, for the Carboniferous and Permian together) and the Triassic. It is now just over 50 years since that concept was elaborated in an account of the work of the Service Géologique de l'Indochine (Fromaget, 1941).

The term “Indosinian” has been widely used, with many different meanings, for folding events in southern, central, southeastern, and eastern Asia that took place during the Permian and Triassic, or during various parts of that time interval. More recently it has been coupled (Dickins, 1985, 1988a, b) with the term “Hunter-Bowen” from eastern Australia to describe a period of worldwide folding and compression, beginning at the mid-Permian, involving a twofold division of the Permian in the Russian type sequence, and continuing to the end of the Triassic. There have been many recent studies of the geology of Indochina, with abundant new data. Within the framework of IGCP Project 272, and with related information from neighbouring countries, we here return to the issue of the Indosinian Tectogeny. This chapter describes some newly collected data related to the issue and presents a preliminary geological correlation for that noteworthy period on a fairly large scale in Southeast Asia.