ameliorated the harshness of the system. They were established quite early in Cochin and Goa, later in Diu, and much later again in Daman and Chaul. This in turn shows two things about the Portuguese system. First, while the Portuguese presence remained fundamentally maritime and littoral throughout, this is not to say that the priorities of this empire did not change, for they did. Around mid century the focus moved from one looking to the carreira and the trade to the metropole towards a much more Asian-centred one where, for example, the aim became to encourage and tax Asian trade rather than try to control it too closely. Second, the Portuguese were unable to conquer large areas of land, and so had to make their money from the sea. Hence this system, and hence their great reliance on maritime revenue. In this they contrast strongly with a landed state, such as Gujarat. The Portuguese Estado da India got fifteen times more revenue from sea trade than from land trade. Portuguese India got about 60 per cent of its total revenue from customs duties, Gujarat got only 6 per cent. Revenues derived by the Portuguese from their control of Diu made up a large part of official receipts. The surplus from Diu, in a good yearlate in the sixteenth century, provided about one-sixth of Goa's total revenue. Similarly, when trade between Gujarat and Hurmuz was blocked by war, the puppet sultan of Hurmuz had to send a much smaller contribution to Goa, as most of Hurmuz's trade was with Gujarat. As a final illustration of the unequal nature of the relationship, the route from Goa to Cambay was the most important of all for the Portuguese, even more than the carreira to Portugal. However, from the Gujarati point of view this trade made up only a small part of total trade, roughly 5 per cent. 14
We will turn to the matter of the success of these aims presently, but first we need to consider two controversial matters. The first area of controversy is, how did the Portuguese justify this system, and second, was this justification one which we can accept? The great chronicler João de Barros set out the justification. The Portuguese were, in Asia, lords of the sea, and made all other ships take a safe-conduct licence, or cartaz, from them. Ships trading to enemies of Portugal could be seized on sight. By common law the seas were open to all, but this applied only in Europe to Christians, who were governed essentially by the principles of Roman Law. Hindus and Muslims, on the contrary, were outside Roman Law as they were outside the law of Jesus Christ, which all men must keep to avoid the eternal fire. Further, Hindus and Muslims had no claim to right of passage in Asian waters, because before the arrival of the Portuguese no one had claimed the sea as hereditary or conquered property. There being no preceding title, there was no present or future right of passage. 15 The concrete manifestation of this came early, when in 1499 the Portuguese king Manuel gave himself the title of 'Lord of the Conquest, Navigation and Commerce of Ethiopia, Arabia, Persia and India'. The late Charles Boxer several times pointed out dryly that at this time the Portuguese had no ships at all east of the Cape of Good Hope.
To investigate the legitimacy of this claim, we need to consider whether there had indeed been any previous attempt to establish control, sovereignty, or even just suzerainty over the Indian Ocean. And we need to decide whether or not the copious violence which the Portuguese used to enforce their aims was new in the ocean.
The juridical matter is rather complicated. When the Portuguese sailed into the Indian Ocean in 1498 they carried with them baggage from the Mediterranean, such as the Roman claim to Mare Nostrum, and generally a tendency towards thalassocracy. As Mollat noted, from very early times in Europe 'the domination of the sea was a natural objective of maritime cities.' 16 In 1498 they entered a body of water which was almost