During the Qing dynasty, Shanghai became one of the most important sea ports in the Yangtze Delta region as a result of two important central government policy changes: in 1684, the Kangxi Emperor reversed the Ming dynasty prohibition on oceangoing vessels—a ban that had been in force since 1525; and in 1732, the Qianlong Emperor moved the customs office for Jiangsu province (; see Customs House, Shanghai) from the prefectural capital of Songjiang to Shanghai, and gave Shanghai exclusive control over customs collections for Jiangsu's foreign trade. As a result of these two critical decisions, Shanghai became the major trade port for all of the lower Yangtze region by 1735, despite still being at the lowest administrative level in the political hierarchy.