Yangzhou, Yangchow or Yang Province was one of the Nine Provinces of ancient China mentioned in historical texts such as the Tribute of Yu, Erya and Rites of Zhou.

There are four different theories regarding the origin of the name "Yangzhou":

Before the Sui dynasty conquered the Chen dynasty in 589, the Chinese terms 揚州 and 楊州 were used interchangeably when referring to "Yangzhou".

According to legend, when Yu the Great (c. 2200–2100 BC) tamed the flood, he divided the land of China into the Nine Provinces, of which Yangzhou was one. Pre-Qin dynasty (221–206 BC) historical texts such as the Tribute of Yu, Erya, Rites of Zhou and Lüshi Chunqiu all mention the Nine Provinces. Yangzhou appears in all these texts even though they provide different names for the Nine Provinces. However, there are three different accounts of the geographical location of Yangzhou.

The Tribute of Yu records that Yangzhou was located between Huai and the Sea. Kong Anguo (fl. 2nd century BC) explained in Shangshu Zhuan (尚書傳) that the text meant that Yangzhou was bordered by the Huai River in the north and the South China Sea in the south. In modern China, the area covered by the ancient Yangzhou corresponds to Jiangsu, Anhui (the region south of the Huai River), Shanghai, Zhejiang, Fujian, Jiangxi, and parts of Hubei, Hunan and Guangdong. The modern city of Yangzhou in Jiangsu is within the ancient Yangzhou's boundaries. However, in later dynasties, the Shangshu Zhuan was proven to be not written by Kong Anguo, hence the book's credibility was largely reduced.

The ancient Chinese encyclopaedia Erya states that Jiangnan was Yangzhou, with the "jiang" (lit. "river") referring to the Yangtze River. Guo Pu (276–324) mentioned in his annotations to the Erya that Yangzhou was defined as the region between south of the Yangtze to the Sea. This area in modern China covers roughly parts of Jiangsu and Anhui that are located south of the Yangtze, as well as Shanghai, Zhejiang, Fujian, and parts of Jiangxi and Guangdong. However, the modern city of Yangzhou in Jiangsu is not within these boundaries, because it is situated north of the Yangtze. Xing Bing (邢昺; 931–1010) wrote in Erya Shu (爾雅疏; Sub-commentary to the Erya) that Jiangnan was a large portion of the ancient Yangzhou, and the lands covered by the ancient Yangzhou was not only limited to Jiangnan. Going by this account, the modern city of Yangzhou was therefore within the ancient Yangzhou. However, as Xing Bing's Erya Shu makes references to Kong Anguo's Shangshu Zhuan, which was verified to be not written by Kong, the Erya Shu's credibility is also disputed.

The Rites of Zhou records, "The southeast is called Yangzhou." By this saying, the ancient Yangzhou would then cover the entire southeastern China, an area larger than the Yangzhou defined in the Tribute of Yu and Erya. This definition is even more sketchy than the above two, because it is unclear whether the modern city of Yangzhou in Jiangsu could be within the ancient Yangzhou or not. The accuracy of the Rites of Zhou itself is also in question. The Lüshi Chunqiu similarly mentioned that "the southeast is Yangzhou."

In 106 BC, during the reign of Emperor Wu (r. 141–87 BC) in the Western Han dynasty (206 BC – AD 9), China was divided into 13 administrative divisions or provinces along with the capital Chang'an and seven commanderies in its vicinity. Each province was governed by a cishi (刺史; Inspector). 11 of them were named after the Nine Provinces mentioned in the historical texts Classic of History and Rites of Zhou. Yangzhou was one of the 11, and it covered parts of modern Anhui (south of the Huai River) and Jiangsu (south of the Yangtze River), as well as Shanghai, Jiangxi, Zhejiang, Fujian, and parts of Hubei and Hunan. The modern city of Yangzhou in Jiangsu was not within the ancient province of Yangzhou; it was in another administrative division called Xuzhou.