Why do people in Changxing County speak Minnan dialect?

During the late Ming and early Qing Dynasties, a large number of Minnan people (mainly Putian, Longxi, Haicheng, Zhangpu, Anxi, Hui 'an and Tong 'an) migrated to Cangnan County, Pingyang County, Yuhuan, Dongtou, Fuding and Xiapu in the northeast of Fujian. Southern Zhejiang and eastern Fujian are geographically connected, with similar accents. This area is collectively called "southern Zhejiang". After being introduced into southern Zhejiang and eastern Fujian, Minnan dialect is different from Minnan dialect because of its own evolution and the influence of surrounding dialects (Ou dialect in southern Zhejiang and Fuzhou dialect in eastern Fujian). Cangnan people used to call this dialect "Min Dialect in South Zhejiang". Compared with Fujian-Taiwan Minnan dialect, the modern Minnan dialect in southern Zhejiang is mainly the merger and degeneration of the entering rhyme and the difference of words. Minnan dialect in southern Zhejiang is a typical Fucheng dialect in Quanzhou, which is highly similar to Quanzhou dialect and can communicate without barriers. Changxing dialect includes Wenzhou dialect, Taizhou dialect and Yixing dialect. The official dialect system includes Henan dialect, Subei dialect, Anqing dialect and Hubei dialect. Minnan dialect refers to Pingyang dialect.