In 1988, an education cooperation agreement was signed between Hai'an County in east China's Jiangsu Province and Ninglang Yi Autonomous County in southwest China's Yunnan Province. Surrounded by mountains, Ninglang was once a deeply impoverished place, but it is rich in wood. The two counties were attached due to frequent timber trade in the 1980s.

Since then, Hai'an has sent 10 batches of 281 teachers to help improve education in Ninglang. Over the past 32 years, teachers from Hai'an have trained over 20,000 junior and high school students and sent over 10,000 students to technical secondary schools and universities.