their families while Zheng Jing brought another 6,000 to 7,000 to Taiwan. Most of the soldiers became farmers. Half of them did not have wives or families. To address the food shortage, Zheng Chenggong instituted a tuntian (military farm) policy in which soldiers worked as farmers when not assigned to active duty in a guard battalion. No effort was spared to ensure the successful implementation of this policy to develop Taiwan into a self-sufficient island, and a series of land and taxation policies were established to encourage the expansion and cultivation of fertile lands for increased food production capabilities. Lands held by the Dutch were immediately reclaimed and ownership distributed amongst Zheng's trusted staff and relatives to be rented out to peasant farmers, whilst properly developing other farmlands in the south. To encourage expansion into new farmlands, a policy of varying taxation was implemented wherein fertile land newly claimed for the Zheng regime would be taxed at a much lower rate than those reclaimed from the Dutch, considered "official land". Teachers were dispatched to various aboriginal tribes to provide them with animals, tools, and know how on advanced and intensive farming techniques. Schools were set up to teach the aboriginal people the Chinese language. Those who refused were punished. Extensive farming spread Han Chinese settlements to the southern tip of the island and as far north as modern Hsinchu, often at the expense of aboriginal tribes. Several rebellions flared up over the course of Zheng rule due to Han Chinese incursions on indigenous ways of life. In one pacification campaign, Liu Guoxuan, stationed in modern Changhua County, killed several hundred Shalu tribes people in modern Taichung, leaving only six alive. The competing Kingdom of Middag was gradually weakened. A series of major conflicts with the Saisiyat people left the Saisiyat decimated and with much of their land under Zheng rule. The details of the conflicts remain uncertain however historians agree that the outcome was negative for the Saisiyat. Chen Yonghua is credited with the introduction of new agricultural techniques such as water-storage for annual dry periods, the deliberate cultivation of sugarcane as a cash crop for trade with the Europeans, and the cooperative unit machinery for mass refining of sugar. The island became more economically self-sufficient with Chen's introduction of mass salt drying by evaporation, creating much higher quality salt than by rock deposits which were found to be very