The term "brass bar" refers specifically to copper-zinc alloy, which began in the Ming Dynasty. Its record can be found in "Ming Huidian": the case of Jiajing, Tongbao 6 million words, practical two-fire brass bar 472.72 kg. Through the elucidation of the composition of copper coins in the Ming Dynasty, the brass rod in the true sense of coin casting mentioned in the Ming Huidian was invented much later than the other copper alloys, which was due to the difficulty of comparing the metal zinc in the brass rod.

During the quotient period, the zinc content of copper ware is very low, usually in the order of 10-z. Among the money in the Western Han Dynasty and Xinmang, there were a few other copper and zinc sums, and the content of zinc in some of the money in the towel reached 7%. However, this does not explain that the brass rod coinage took place in the Xinmang period of the Western Han Dynasty. Because these copper-zinc alloys are extremely individual signs, their zinc content is much smaller than that of brass bars in the true sense of 15-40% zinc content.

Therefore, we believe that these zinc-containing copper coins occurred during the application of copper-zinc symbiotic minerals in the near-mountain coinage casting in the Han Dynasty. According to the investigation of the relevant mines, it was found that there are abundant copper-zinc symbiotic ores in Changwei, Yantai, Linyi and Hubei provinces in Shandong Province, which makes the smelted copper contain a small amount of zinc. By the Tang Dynasty, due to the standardization of money-casting materials, the zinc content in the money was trace.