"At least seven layers of brick structures were found during excavation which was started in three six square metre trenches on March 25 last," exploration officer of Ambari excavations of the State Archaeology Department Dr H N Dutta said here on Tuesday.

On the basis of preliminary investigation, different layers of brick structure suggest that human civilisation through different ages flourished here, Dutta said.

"However, a final picture on the history of the area would emerge only after extensive examination and correlation of evidences found during excavation," he pointed out.

The evidences gathered so far during the various phases of excavation carried out in the area since 1969 suggest that human habitation in the area might date back to the 8th century.

Dutta said this year's excavation had exposed naturalsoil in one of the trenches and this would help in determining the first human habitation period in the area.

Several metallic coins, including a copper coin of British East India company, red beads, fragments of green-base pottery, kaolin and terracotta pottery have been found in the excavations.