During the late Ming dynasty, due to political chaos, there was increased migration from southern Fujian and eastern Guangdong to Taiwan. The earliest immigrants who were involved in the development of Taiwan included pirate-merchants and Zheng Zhilong. In 1621, Chinese Peter and his forces, hailing from Zhangzhou, occupied "Ponkan" (modern-day Beigang, Yunlin) and started to develop "Tirosen" (modern-day Chiayi). After the death of Peter and another pirate, Li Dan of Quanzhou, Zheng sought to dominate the Strait of Taiwan. By 1628, he had grown so powerful that the Ming court bestowed him the official title, "Patrolling Admiral".