The Center for Archaeological Science, Sichuan University published findings revealing the production model of bronze arrowheads in the State of Chu.

Recently, Professor Hai-chao Li's team at the Center for Archaeological Science, Sichuan University, published an article titled "The production of bronze weapons in the Chu state: a case study of bronze arrowheads excavated from the Yuwan cemetery in Hubei, China," focusing on the manufacturing technology, alloy composition, and source of ore materials of bronze arrowheads unearthed from the Yuwan cemetery in Hubei. Based on this research, they initially discussed the production model of bronze weapons in the Chu state. The article was published in Archaeological and Anthropological Sciences.

The Yuwan cemetery is located on a hillside in Leidu Village, Zengji Town, Shayang County, Jingmen City, Hubei Province, covering an area of approximately 40,000 square meters. From November 2016 to March 2017, the Department of Archaeology, School of History and Culture, Sichuan University, conducted a comprehensive exploration and archaeological excavation of the cemetery, clearing a total of 57 Chu tombs. A total of 16 arrowheads were unearthed (Figure 1), which can be divided into 4 different types according to the differences in the arrowhead body, dating from the early, middle, and late Warring States period.

Figure 1 Bronze arrowheads unearthed from the Yuwan cemetery

Through the analysis of the alloy composition of the bronze arrowheads, the research team found that most of these arrowheads had good mechanical properties. In addition, some arrowheads had tangs remaining in the sockets, which were identified as iron through scanning electron microscopy and energy spectrum analysis. Combined with the characteristics of the shape and the literature records, it reveals that the evolution of bronze arrowheads from bi-bladed to tri-bladed, the continuous lengthening of the tang, the emergence of iron tangs, and the high-tin and low-lead alloy composition all reflect the improvement of the arrowheads' killing performance. Metallographic analysis shows that the arrowheads were all cast, and the specific production methods can be divided into integral casting and separate casting. Separate casting can further improve production efficiency and facilitate large-scale mass production.

In order to discuss the production model of arrowheads, the research team conducted trace element and lead isotope analysis (Figure 2) based on the typological analysis of bronze arrowheads. The results show that these arrowheads were not produced in a single batch, which means that the production frequency of bronze arrowheads in the Chu state during the Warring States period was high. This is also consistent with archaeological materials. Compared with other cultures of the same period, the proportion of bronze arrowheads buried in Chu tombs is much higher. This practice of using a large number of bronze arrowheads as burial objects undoubtedly places higher demands on the production efficiency of arrowheads. In addition, during the Warring States period, the frequency and scale of wars in the Chu state further expanded, which inevitably led to a sharp increase in the demand for the number of bronze weapons. Therefore, only high-frequency, multi-batch production models and abundant sources of ore materials can meet this need.

Figure 2 Comparison of lead and tin content of different types of bronze arrowheads from Yuwan

In order to further trace the source of the lead used in the arrowheads, the research team compared and analyzed the lead isotope ratios of Yuwan arrowheads with published data of Chu bronze wares and some mines, indicating that the Chu state during the Warring States period had a strong metal resource supply network (Figure 3). In addition to using metal resources within the Chu state, the rulers of Chu could continuously transport local metal resources to the Chu state for the production of bronzes by occupying areas with abundant metal raw materials, such as the Nanling Mountains, western Henan, and northern Jiangxi.

Figure 3 Comparison of lead isotope ratios of Yuwan bronze arrowheads and mine data

This article provides new evidence and perspectives for studying the weapons of the Chu state during the Eastern Zhou Dynasty, showing the complexity of the manufacturing technology, ore material sources, and production model of Chu bronze weapons. In subsequent work, with the continuous accumulation of scientific and technological data and the development of experimental archaeology, it is believed that the research on Chu weapons can be further promoted. Associate Professor Ke Zhang of Hunan University and Qiang Li, a doctoral student of our college, are the co-first authors of this article. Professors Bin Bai and Hai-chao Li of our college are the co-corresponding authors of this article, and Jian He, a master student of our college, is a co-author of this article.