The history of Gan Chinese, a variety of Chinese spoken in modern-day China, stretches back to the beginning of the Qin dynasty. This long stretch of time is divided into Old Gan, late Old Gan, and Middle Gan periods.
Old Gan (上古贛語, Song-gu Gon-ngi) or Proto-Gan (原始贛語, Ngien-si Gon-ngi) was spoken between the beginning of the Qin dynasty to the latter part of the Han dynasty.
In the year of 221 BC, General Tu Sui (屠睢) was sent on behalf of the Qin dynasty to the south of China in order to conquer the territory of Baiyue. 500,000 soldiers then settled down at Yugan, Nankang and three other places. This formed the initial Chinese population in Jiangxi. In 202 BC, Yuzhang Prefecture (豫章郡) was set up by the Han dynasty. Following this, the local population increased rapidly.
Late Old Gan (中古贛語, Zung-gu Gon-ngi) was spoken between the 3rd and 6th centuries. It was largely sinicized by new settlers from the Central Plain. Some scholars consider late Old Gan, together with Hakka Chinese and the Tongtai dialect of Jianghuai Mandarin to have been the lingua franca of the Southern Dynasties.
However, late Old Gan was still distinctly different from the official language. History of Southern Dynasties records that
Hu Xiezhi (胡諧之) of Nanchang, the Emperor wants to bestow a noble marriage on him. He sends several persons of the Palace in order to teach his children the [official] language. Two years later, the Emperor asks him if the language has been standardized in his family, and Hu answers that his family hasn't acquired the official language while those imperial envoys have already been Ganized.