The maritime influence.

Special circumstances affecting Shrivijaya-Palembang toward the end of the 7th century are consistent with this conclusion. In the centuries before the Chinese undertook long voyages overseas, they relied on foreign shipping for their imports, and foreign merchants, trading with China, required a safe base in Indonesia before sailing on to China. This seaborne trade, regarded in China as "tributary" trade with the "emperors' barbarian vassals," had developed during the 5th and 6th centuries but languished in the second half of the 6th century as a result of the civil war in China that preceded the rise of the Sui and T'ang dynasties. Chinese records for the first half of the 7th century mention several small harbour kingdoms in the region, especially in northeastern Sumatra, that were pretending to be Chinese vassals. The rulers of Palembang, hoping for a revival of trade under the new T'ang dynasty, must have been anxious to monopolize the China trade and eliminate their rivals. They succeeded in doing this. Before I-ching left Southeast Asia in 695, Shrivijaya was in control of the Strait of Malacca; the ruler's determination to control all harbours in the region that might compete in the China trade explains his militancy, as shown in the Old Malay inscriptions.

The subsequent power of the maharajas of Shrivijaya depended on their alliance with those who possessed warships. The fact that Arab accounts make no mention of piracy in the islands at the southern end of the Strait of Malacca suggests that the seafaring inhabitants of these islands identified their interests with those of the maharajas, refraining from molesting merchant ships and cooperating in controlling Shrivijaya's potential competitors in northern Sumatra. The maharajas offered their loyal subjects wealth, posts of honour, and--according to the inscriptions--supernatural rewards. But the grouping of maritime Malays in this geographically fragmented region survived only as long as the Palembang entrepôt was prosperous and its ruler offered enough largess to hold the elements together. His bounty, however, depended on the survival of the Chinese tributary trading system, which needed a great entrepôt in western Indonesia. Early Malay history is, to an important extent, the history of a Sino-Malay alliance. The maharajas benefited from the China trade, while the emperors could permit themselves the conceit that the maharajas were reliable imperial agents.

The Palembang rulers' exact span of territorial influence is unknown. The Banka Strait and the offshore islands at the southern entrance of the Strait of Malacca would have been essential to their maritime power. According to the 7th-century inscriptions, the rulers also had influence in southern Sumatra on the Sunda Strait. Elsewhere in the hinterland, including what became known as Malayu in the Hari River basin, their authority would have been exercised by alliances with local chiefs or by force and always with decreasing effect the further these areas were from Palembang.

Malay unity under the leadership of the maharajas was inevitably undermined when, as early as the 10th century, Chinese private ships began to sail to centres of production in the archipelago, with the result that the Chinese market no longer depended on a single Indonesian entrepôt. Toward the end of the 11th century, Shrivijaya-Palembang ceased to be the chief estuary kingdom in Sumatra. Hegemony had passed, for unknown reasons, to the neighbouring estuary town of Jambi, which was probably controlled by the great Minangkabau country of Malayu in the interior. With the decline of the tributary trade with China, a number of harbours in the region became centres of international trade. Malayu-Jambi never had the opportunity to build up naval resources as Shrivijaya-Palembang had done, and in the 13th century a Javanese prince took advantage of the power vacuum.