The suspects, all natives of the eastern Jiangsu Province, fled after the theft. They were caught in Dafeng and Yancheng of Jiangsu last week and were taken back to Qinghai on Monday, along with the stolen articles.
The suspects pleaded guilty to stealing cultural relics, the spokesman said.
The case was being further investigated.
The Dongdre Lamasery has a history of more than 700 years and the stolen articles were precious relics, said Dongdre Rinpoche.