Why Jiujiang dialect belongs to Jianghuai Mandarin?

In the pre-Qin period, Sichuan held the Bashu language of the Burmese language group. 3 16 years ago, the Qin dynasty destroyed Bashu and immigrated. Bashu officials began to speak Mandarin in the Central Plains, and Han Chinese migrated to Sichuan in the Han Dynasty. Zhuge Liang also organized immigrants to Sichuan. In Yongjia Rebellion, Late Tang Rebellion and Jingkang Rebellion, people from the Central Plains moved to Sichuan in succession. In the Yuan Dynasty, Liang Yi dialect had been formed in Sichuan, which combined Bashu dialect and Shaanxi dialect. Due to the wars and natural disasters in the Southern Song Dynasty and the end of Yuan Dynasty, the population of Sichuan decreased sharply. At the end of Yuan Dynasty, the immigrants who entered Sichuan with the Ming Dynasty came from Hubei, while those who entered Sichuan at the beginning of Ming Dynasty mainly came from Hubei. These Hubei immigrants (now called old households and aborigines by Sichuanese) were mainly Macheng in Jianghuai area, and most Macheng people were originally from Jiangxi. Based on Southwest Mandarin, Sichuan dialect in Ming Dynasty absorbed the mixture of Gan dialect and Liang Yi dialect and formed Sichuan dialect. In the late Ming and early Qing dynasties, the population of Sichuan was hit hard again, which led to Huguang (especially Hubei) filling Sichuan again. In the Ming Dynasty, Sichuan dialect and Hubei dialect merged into today's Sichuan dialect. In the early Ming Dynasty, a large number of people immigrated to Yunnan and Guizhou in the form of garrison, while in the Qing Dynasty, the immigrants accepted by Yunnan and Guizhou mainly came from Sichuan, Hunan and Jiangxi, so the southwest Mandarin of Yunnan and Guizhou was also greatly influenced by Jianghuai Mandarin and Gan Dialect. Wuhan dialect belongs to southwest mandarin and is influenced by various dialects, so the words used may be somewhat the same.