Japanese colonial rule was instrumental in the industrialization of the island, extending the railways and other transport networks, building an extensive sanitation system, and establishing a formal education system in Taiwan. Japanese rule ended the practice of headhunting. During this period the human and natural resources of Taiwan were used to aid the development of Japan, and the production of cash crops such as rice and sugar greatly increased. By 1939, Taiwan was the seventh-greatest sugar producer in the world. Still, the Taiwanese and aborigines were classified as second- and third-class citizens. After suppressing Chinese guerrillas in the first decade of their rule, Japanese authorities engaged in a series of bloody campaigns against the mountain aboriginals, culminating in the Musha Incident of 1930. Intellectuals and labourers who participated in left-wing movements within Taiwan were also arrested and massacred (e.g. Chiang Wei-shui and Masanosuke Watanabe).