How were rubber trees introduced to Hainan in the early 20th century?

In the early 20th century, rubber trees were introduced to Hainan by Chinese emigrants who were returning to the island from Malaysia. Following this initial introduction, the cultivation of rubber and other tropical goods was further expanded during the Japanese occupation of the island between 1939 and 1945. After 1950, the development of state farms helped establish the industry, and today Hainan produces the majority of China’s rubber.12