Most likely the earliest trade routes of the Indian Ocean developed about 5000 years ago between the Indus Valley and the Persian Gulf, possibly contemporary with initial Austronesian expansion in Southeast Asia. However, Indian Ocean boatbuilding seems to have contributed nothing to Austronesian designs until effectively historical times. Whether the original Austronesian and Indian Ocean hull was a dug-out log extended upwards by a plank or two, or whether it was built entirely of planks, the seams must have been sewn. It is astonishing how widespread were sewn planks, over Europe, Asia and Oceania, and how long they persisted into modern times, with interesting variants. We can assume that this common heritage extended to Southeast Asia and that the Austronesians also acquired it. In early Egypt, boatbuilders evolved another technique to hold planks edge-to-edge by using flat tenons embedded in slots in the edges of the planks and then locked in with transverse wooden pins. In Mesopotamia and the Indus Valley they used dowels or treenails within carved hardwood planks which were placed edge-to-edge and then sewn. These additional techniques must have been very ancient but they are linked to the use of bronze tools.
The fixed mast, dowelling techniques,[1] the quarter rudder and the trapezoid sail appear to have spread eastwards into Indonesia from the Indian Ocean during the past 2000 years, since the initiation of trade through the Straits of Malacca. Before the arrival of western explorers these details spread no further than the early trade routes to the Philippines and New Guinea.
Theories that Austronesian rigs were derived from those of the Indian Ocean, or even from Egypt, are mistaken because the Austronesians had left Mainland Asia long before contacts spread eastwards. On the contrary, the westward spread of the Austronesian triangular sail into the Indian Ocean about 200 BC provides us with the probable origin of the Arab triangular lateen sail that spread into Egypt and even into the Mediterranean by late classical times, say AD 200. A thousand years later the Portuguese adopted the lateen on the mizzen masts of their caravels, enabling them to manoeuvre closer to the wind and reach the Pacific.
Although influences from the Indian Ocean were too late to influence the Pacific Austronesians, Sanskrit words and possibly some rigging techniques could have started to spread east of Peninsular Malaysia by 200 BC. Trade routes were also open between Vietnam and eastern Indonesia about 200 BC, as shown by the distribution of the Dong Son bronze drums along the natural sea route dictated by the monsoons in the South China and Java Seas. Recent excavations at Sembiran in Bali have also revealed evidence of drum casting and deposits of South Asian rouletted ware pottery, most likely dated before AD 200 (Ardika and Bellwood 1991). Annual trade between China and India through the Malacca Straits had opened by about 200 BC. Perhaps by that time Austronesian sailors were regularly carrying cloves and cinnamon to India and Sri Lanka, and perhaps even as far as the coast of Africa in boats with outriggers. Certainly they have left numerous traces in canoe design, rigs, outriggers and fishing techniques, and a mention in Greek literature (Christie 1957).
About 1300 years ago or less (Adelaar, this volume), Austronesian-speaking people from Indonesia reached Madagascar and some of the small islands off the east coast of Africa, at that time all apparently uninhabited. Although they later mixed with African Bantu people they preserved their languages and canoe styles. Whether they navigated in both directions in short stages along the coasts of Africa and South Asia, or directly across the Indian Ocean, is unknown, but both routes are probable. Not all the islands of the Indian Ocean were colonized; for example, the Mascarene group (remember how the dodo survived in seclusion there) and the Seychelles were not inhabited when occupied by the French in the seventeenth century, although they were known to explorers and pirates before that. The incomplete coverage suggests that the Malay wanderers did not regularly cross the central Indian Ocean, where we find none of the folklore of navigation and voyaging that was abundant until recently among Pacific Islanders.