This article will concentrate on one aspect of a major question in Southeast Asian maritime history: an attempt will be made to describe and determine the origins of the type of ship that was the main form of transport for the trade of the maritime kingdoms of the western half of Southeast Asia until the arrival of the Europeans in the sixteenth and seventeenth centuries. Surprisingly enough — if the general importance of the commercial network of maritime Southeast Asia is considered — such a study has not yet been attempted. The very few authors dealing with the economic history of the region are usually content to dismiss the problem by saying that the ships are locally called “junks”, and that their tonnage is small. (The reader is thus left with the idea that Chinese ships were being used, since the word “junk” has long been applied almost exclusively to this very specific type of ship.) The general conclusion of this study is that Southeast Asian maritime powers built, owned, and operated ocean-going ships of respectable size as early as the first few centuries of the first millennium A.D. Needless to say, this has a considerable historical significance (which will not be examined here).