Indonesia learned the metal work crafts from Southern Chinese and Southeast Asian traders during the late Bronze age, several hundred years before the birth of Christ. These influences have been inferred from archeological digs that have uncovered dongson drums, jewelry, weapons and other artifacts clearly bearing "imported symbols." Excavations of ancient graves have also turned up artifacts from this period than show remarkable similarities with similar items from modern day China and India.
Over time, the metalworking skills of the Indonesian people grew, no doubt added by continuous contact with outsiders seeking trade in spices and other items. Gold and silver, which continue to be mined in Indonesia, were in no short supply by the time the Majapahit Empire emerged in Java (1300s) and moved into Bali. By the time the empire had failed, Bali had become the center of Indonesia's silversmithing and gold work activities.
One cannot easily discern how past influences have shaped current silver work practices in Bali. It is important to keep in mind that Bali, far from being an isolated island culture, has had vigorous contact through trade with many cultures over many, many centuries. Indeed, Indonesia as a Dutch colony as of 1602 and controlled much of the nation for 350 years. As such, European silverwork traditions and standards were no secret to the Indonesians, many of whom no doubt produced for export.