This is one example of many types of bronze ritual weapons used in burials of the bronze-making Dong Son culture. Knives, axe heads and arrow heads have been found with other bronze objects such as ritual drums in burials in the Red River Delta region. Stone moulds have also been found with carved impressions that indicate they were used to cast these weapons. Lost wax casting is another method used for pieces that have more intricate three-dimensional designs. The sophisticated technology used in bronze-casting suggests that Dong Son society was advanced enough to have specialists who would have worked full-time in this field. This can be seen in the spread of bronze goods and technology throughout the Southeast Asian region.