In 1850 Southeast Asia had a population of just forty million or so. The greatest concentrations of population were in Java (with perhaps a quarter of the total), Madura, Bali, the rice basins of the Menangkabau highlands of west Sumatra, the dry zone of the Irrawaddy, the flood plain of the Chao Phraya, the coast of Vietnam, Luzon, and southwest Sulawesi. There were pockets of population in the Straits Settlements of Singapore, Penang, and Malacca and numerous small sultanates in the island world from Aceh in the west to Ternate in the east. In contrast, large sections of Southeast Asia such as much of the area along both sides of the Straits of Malacca, most of Borneo, and most of the eastern island world were very sparsely populated. The great majority of the people of the region were peasant farmers, growing rice and other food crops for their own consumption and usually producing food and other goods for their overlords as well. A very small proportion of the population lived in cities and towns or worked in mines and plantations. The people of the region lived within or on the fringes of a very large number of political units in which power was, at least from our vantage point, highly decentralized, though less so in the few areas then under colonial rule such as Java, the Straits Settlements, Luzon, and the Visayas than in most of the rest of the region. In this world of scores of polities and thousands of islands a powerful unifying influence was the sea. It was by sea that people travelled long distances, and it was by sea that nearly all the long-distance trade was conducted, not only within the region but also with China, India, and Europe. Trade in sea-going sailing vessels and, by 1850, a tiny number of steamships was the lifeblood of such port cities as Singapore, Batavia, Surabaya, Makassar, and Manila.
And it was the sea that provided animal life that people exploited both for food for themselves and for products that they could trade with others. For many people the capture of marine life was not their main activity. They were primarily agriculturalists and fished when planting and harvesting did not demand their full attention. For others, however, fishing was their main source of livelihood.