When historians discuss the revolutionary changes associated with guns, they tend to focus on Europe's early modern period (1500–1800), but the late medieval period (1300–1500) was arguably more significant. It was then that guns became widely adopted, grew in power and size, and, finally, toward the 1480s, took on their classic form, which would remain largely the same for the next three centuries. The work of scholars such as Kelly DeVries, Robert Smith, Bert Hall, and Clifford Rogers has examined these developments in Europe, establishing that the late medieval period was a key watershed in the history of guns, as important as – perhaps more important than – the early modern period. But what is intriguing is that this was not just true of Europe. Recent work by historians of China has demonstrated that during the thirteenth, fourteenth, and fifteenth centuries Chinese guns were also evolving rapidly, transforming East Asian warfare.

Reading the evidence from China in conjunction with that from Europe reveals puzzles that I believe illuminate both historiographies, because although gunpowder warfare evolved rapidly in both Far Eastern and Far Western Eurasia, it also evolved differently: Western Europeans focused on gunpowder artillery; Chinese focused on smaller guns, particularly firearms (handheld guns). Thus, whereas it seems that firearms did not play a major role on Western European battlefields until the mid-1400s at the earliest (they were present, but in relatively small proportions), there were around 150,000 dedicated firearms units in the Chinese armed forces by the 1370s, a proportion of 10 percent of infantry forces, a ratio that would rise to 30 percent by the mid-1400s. This latter figure would not be matched in Europe until the mid-1500s. In contrast, wall-smashing gunpowder artillery began to appear in Europe by the late 1300s and did not appear in Chinese warfare until introduced by Europeans, starting in the 1500s.

What accounts for these divergent developments? And, equally importantly, why in Europe did all forms of guns – handheld and artillery – improve so rapidly in the second half of the 1400s, whereas in China development slowed or ceased, so that by the early 1500s Chinese recognized that European guns were superior and began adopting them?