Uncovering history: A stone bridge leading to Sy Nhiep Temple. This part of Luy Lau Citadel is still intact. — Photo vtv.vn

HA NOI (VNS) — Experts excavating an ancient citadel found new evidence on how traditional bronze drums were made, and were able to learn more about the process.

The Viet Nam National Museum of History held a seminar yesterday for cultural researchers and archaeologists, who reported the results of excavations in Thanh Khuong Commune, Thuan Thanh District, the northern province of Bac Ninh, and at Luy Lau Citadel.

Under an agreement to strengthen and promote academic exchange between Viet Nam and Japan, a team from the history museum and the University of East Asia in Japan has started excavating the Luy Lau archaeological site in a project lasting until 2019. The university's Professor Huang Xiaofen led the team.

Museum officer Truong Dac Chien, one among excavators, presented pieces of bronze drum moulds and traces of drum casting materials to the seminar's participants.

Dong Son drums (also called Heger Type I drums) are bronze instruments created during the time of Dong Son, a developed Bronze Age culture that lived in northern Viet Nam. The drums symbolise the culture and exemplify fine metalworking.

According to Chien, the drums were both musical instruments and cultural objects. They were decorated with geometric patterns, scenes from war and daily life, animals and boats.

"This is the first time we found a large amount of debris from the drum-casting process," Chien said.

"They are all in a stable geological layer dating from the 4th century. Now we can affirm the time period during which Dong Son drums were made and the casting method. We determined that the drums belong to the native culture."

Before, archaeologists believed that ancient people used wax or pottery to make moulds for casting drums. They supposed that when the process was complete, the mould would be broken and the wax melted down. That's why it's hard to find traces of the bronze drum casting process.

"The missing knowledge of how, when and where bronze drums were made left a gap in scientific research," Chien said.

"Scientists have wondered whether Dong Son drums were made at the site or brought from other regions."

Bronze drum casting started with shaping a clay mould on a turning table. Then the caster would cover the mould with another layer of clay, leaving a space between the two layers to pour melting bronze inside. The caster would carve designs into the two pottery layers and the drum's face.

The turning table created a centrifugal force to let bronze spread evenly throughout the mould.

Chien said the archaeologists found pieces of the pottery moulds with patterns on them, a funnel for pouring liquid bronze and a bolt from the turning table's axle.

A region's relics

Prof Huang called Luy Lau Citadel an important relic in the region.

"Luy Lau was a political and cultural centre for the country 2,000 years ago," Huang said.

"It's rare to see a vestige of an ancient urban area with administrative functions, a military base, a residential area and bronze-casting workshop. It's also uncommon to see an urban area so close to a graveyard. The two sites have a close relationship that requires scientists to excavate and research both to be able to see the Citadel and all its history clearly."

Apart from bronze drum casting leftovers, scientists also found evidence of the outer and inner layers of the citadel.

In the near future, the archaeologists will expand their excavation to try to find traces of a harbour on the Dau River that was first spotted in satellite photos.

"The group of Japanese experts specialise in different fields such as archaeology, geology, cultural research and remote sensing," said Chien.

"Thanks to the partnership with them, we can carry out professional research and gain a panoramic view of the relic." — VNS