Why doesn't Nanjing speak Wu? When did Nanjing change from a Wu dialect area to a Putonghua area?

Before the Eastern Jin Dynasty, Nanjing belonged to the Wu dialect area. During the Yongjia Rebellion at the end of the Western Jin Dynasty, there were more than 900,000 northern immigrants in Dunan, Guan Yi, far exceeding the native people who spoke Wu. Wang Dao, the prime minister of the Eastern Jin Dynasty, ruled out the northern gentry's mocking of Wu language, and contacted the southern gentry for the Jin Emperor Si Marui. Because there are more immigrants from the north, the northern Mandarin brought by the immigrants from the north is better than the local Wu dialect in Nanjing. After several generations, Nanjing gradually changed from a Wu dialect area to a Putonghua area.