 Complete the following phrase:  During the Ming dynasty, the area of present-day Taishan was carved out of Xinhui County on 12 February 1499 as Xinning County. By the 19th century, Xinning was already a source of migrant and emigrant workers, but a series of subsequent natural and political disasters in the exacerbated the situation. Aside from the disruption of the Sea Ban regulations Haijin themselves, their revocation led to an influx of northern settlers who began long-running feuds with the returning locals; this erupted into full-scale war in the 1850s and 60s. The 1842 Treaty of Nanking that ended the 