Indian ports that demanded high taxes from docking ships invariably lost out to "free ports" - i.e. ports that demanded very low tariffs from docking ships. In fact, several of the Indian ocean ports were politically neutral entities - giving free and equitable access to shippers of varied nationalities and religious affiliations.
Whereas pre-15th century Arab and Chinese geographical texts spoke of various natural hazards involved in long-distance shipping, they did not cite any significant political or military impediments to undertaking long-distance voyages other than the risk from pirates. Thus, evidence left behind by chroniclers such as Marco Polo, Ibn Batuta, Persian ambassador Abdur Razzaq, the Venetian Nicolo Conti, and Genoan Santo Stefano - all indicate that the Indian Ocean was the scene of thriving trade in the 14th and 15th centuries.
But once the Portuguese had discovered their new route to India, they displayed considerable zeal in seizing the most profitable ports of East Africa, the Persian Gulf, and the Saurashtran, Konkan and Malabar regions in India. A chain of fortified coastal settlements backed by regular naval patrols allowed the Portuguese to gradually eliminate many rivals, and enforce a semi-monopoly in the spice trade by the middle of the 16th C. Local traders were coerced into buying safe passes and paying customs duties to the Portuguese. However, this attempt at a monopoly was challenged by the maritime powers of North Sumatra based in Aceh, as well as by the Omanis, and by Gujarati traders. And as the Portuguese expanded with settlements in South East Asia, China and Japan - the Western monopoly became harder to maintain.
Initial success came to the Portuguese because they had been shrewd enough to develop a strategy of divide and conquer - first concentrating on isolating Muslim traders from the Hindu monarch of Calicut and demonstrating their fire power by launching a two-day bombardment of the vital port city (which was then the largest spice market of the Indian Ocean). These intimidating tactics worked in the favor of the Portuguese who repeated this strategy at other key trading destinations. In 1510, Bijapur's Adil Shahi ruler ceded the control of Goa to the Portuguese. Having realized that the bulk of trade moving out of India landed at one of three ports in the Indian Ocean - i.e. Hormuz in the Persian Gulf, Aden on the Red Sea, and Malacca in the Malay Peninsula - Goa's Indian Governor, Alfonso Albuquerque then shifted his attention to capturing each of these crucial ports. Malacca fell in 1511 and Hormuz in 1515. Only Aden proved elusive.
In 1505, the spice trade from Asia to Europe was declared a 'royal monopoly' by the Portuguese, who saw in this the possibility of extorting tribute through military means. Once Hormuz and Malacca came under the military and political control of the Portuguese, the Portuguese then attempted to expand their monopoly to the inter-Asian trade. For this they needed to seal off independent access to the Gujarati traders who although cut off from Malacca could...