The origin of gunpowder based weaponry in Nusantara archipelago can be traced from the late 13th century. The Mongol invasion of Java brought gunpowder technology to Java in the form of a cannon (Chinese: "Pao"). This resulted in the development of Javanese breech-loading swivel gun, the cetbang. By the 1300s, the Majapahit fleet had already started using them as a naval weapon. The Javanese mastered the art of bronze-smithing and use of a central arsenal fed by a large number of cottage industries within the immediate region. Documentary and archeological evidence indicate that Arab traders introduced gunpowder, gonnes, muskets, blunderbusses, and cannons to the Javanese, Acehnese, and Batak via long established commercial trade routes around the early to mid 14th century.