Instead, they hauled ore or iron slag to the siege site and cast guns in place as needed. This partly solved the problem of transporting huge siege guns. In China artillery progress paralleled changes occurring in Europe, though it remains unclear to what extent one civilization influenced trends or ideas in the other, or even if they did. At the end of the 15th century some Chinese guns were bigger than the greatest bombards then made in Europe.
Chinese armies also mounted greater numbers of small cannon, many on two-wheeled gun carriages that made them mobile in the field or at least speeded their arrival at sieges. This progress reflected China's advanced knowledge of metallurgy and its vastly greater wealth. Chinese smiths even experimented with two-barreled cannon which faced in opposite directions while mounted on a rotary, a clever trick which doubled the rate of fire. The Chinese also invented a form of grapeshot as early as the 13th century and a form of exploding shell well before these were seen in Europe. Chinese armies also used rocket artillery as an adjunct to their cannon, which European armies did not.
Still, it was developments in Europe that ultimately spread to reshape world military practice and history. The key advances in development of artillery, in the sense of large-bore metal tubes firing high-velocity solid or explosive projectiles, along with the skilled and specialized troops and the science of ballistics that accompany such guns, took place in Europe during the 14th and 15th centuries. Until then, Europe's technology had just kept pace with China's (for instance, in both regions the hoop-and-stave or forged gun method of assembling large cannon was used, with casting reserved for smaller pieces). But thereafter Europe pulled ahead to stay.
Moreover, cannon became central in a global military revolution as casting technology spread to other continents and civilizations from the decks of European armed merchants and warships, along with European traders, mercenaries, renegade technicians, and priests. In 1511 the Portuguese brought their most modern cannon to China, where they were quickly recognized as superior to domestic models. The Jesuits were especially important in transferring casting technology to the Chinese and Japanese in the 16th century. The dual mode of technology transfer-slowly by land across central Eurasia, more rapidly by sea-meant that artillery might be technically decades ahead in one area compared even to a nearby region.
Thus, the Moors in Spain probably used gunpowder weapons as early as the 12th century, and certainly Muhammad IV of Granada used it at Alicante in 1331 and after. But after that they did not have access to the advanced models of their Christian enemies. Various Turkic peoples acquired artillery in the 14th century, possibly directly from the Chinese. It is known that Turks introduced artillery to India at the latest by 1368 and that cannon were soon in wide use in the Deccan by Muslims and by Hindu Vijayanagar. Turkish technology was dominant in north India into the 17th century, reflecting Muslim power and external contacts.
That included a tendency to gigantism in artillery, with za few monster bombards exceeding 50 metric tons of iron. In southern India more modern European gun types were available as contact was made with Portuguese, French, Dutch, and English ships and traders along the coast. Ceylon (Sri Lanka) became a major center of European-style cannon manufacture in the Indian Ocean during the 16th-17th centuries. Similarly, in SE and North Asia most local powers sought to set up their own foundries, often hiring renegade gunsmiths to help them (Venetians in Malabar, Dutch in Japan, Portuguese, English or Dutch in SE Asia, Italian and German Jesuits in China). European powers also set up foundries in Asia to cast guns for their fortification and other local needs: the Dutch had a foundry in Hirado, Japan, then a much larger operation in Batavia; the Portuguese had a cannon foundry in Macao; the Spanish cast cannon for their Asian forts and ships in Gavite, in the Philippines.
