Although the rates of such taxation are unknown as there are no records, the Dutch must have made a lot of profit from the export duties received by Chinese and Japanese traders. This resulted in the friction between the Dutch and the Japanese causing the Hamada Yahei incident in 1628. Another form of taxation was the poll tax which the Dutch levied on every person who was not Dutch and above six years of age. At first, the rate of the poll tax was set at a quarter of a real whereas the Dutch, later on, increased the rate to a half real. In 1644, the total amount of the poll tax imposed was 33,7000 reals and in 1644, over 70,000 reals were imposed. Coupled with restrictive land tenancy policies and extortion by Dutch soldiers, the tax provided grounds for the major insurrections of 1640 and 1652. The Dutch imposed a tax on hunting as well. They sold a license to dig a pit-trap for 15 reals a month and a license for snaring was sold for one real. During the hunting season between October 1638 and March 1639, the total amount of the hunt tax was 1,998.5 reals. There were no licenses for fishing while it was taxed. By 1653, the Dutch revenue from Taiwan was estimated at 667,701 gulden 3 stuiver and 12 penning, including the revenue of 381,930 from tradings. This indicates that for Dutch, taxation became the important way of making profit in Taiwan. Demographics Prior to the arrival of the Dutch colonists, Taiwan was almost exclusively populated by Taiwanese aborigines; Austronesian peoples who lived in a hunter-gatherer society while also practicing swidden agriculture. It is difficult to arrive at an estimate of the numbers of these native Formosans when the Dutch arrived, as there was no island-wide authority in a position to count the population, while the aborigines themselves did not keep written records. Even at the extent of greatest Dutch control in the 1650s there were still large regions of the island outside the pale of Dutch authority, meaning that any statistics given necessarily relate only to the area of Dutch sovereignty. Ethnicity The population of Dutch Formosa was composed of three main groups; the aborigines, the Dutch contingent, and the Chinese. There were also a number of Spanish people resident in the north of the island between 1626 and 1642 in the area