Archaeologists in the central province of Ha Tinh said Friday they have discovered the remains of an ancient citadel dating back more than 1,600 years.

The 1km-long section of the citadel, built of stones, was found at the top of But Mountain Pass in Ky Anh District.

The archaeologists said it the section was part of a 30km-long citadel built between 345 and 375 A.D. to protect the country from foreign forces.

The citadel, which leaned on a mountain range and ran through three villages, was made of stones and earth, they said.

A local official said the citadel used to be covered by trees until locals discovered and took stones from the citadel to build a dike several years ago. This practice was stopped by local authorities later.

Le Ba Hanh, deputy director of Ha Tinh Museum, said the discovery was good news for historical researchers.