The skull was found in the M1401 tomb in Guyuan City in northwest China's Ningxia Hui Autonomous Region.
"The man had a protruding nasal bone and a sunk nasion, which are typical features of Europeans," said Zhang Quanchao, professor with the Research Centre for Chinese Frontier Archaeology of Jilin University.
Zhang believes the skull belonged to a 40-year-old man of European origin, state-run Xinhua news agency reported.
"If we can find his teeth and more bones, we will have a more precise judgement about his age," he said.
According to Zhu Cunshi, head of the archaeological team, more than 40 clay figures, copper coins and a number of murals were found in the tomb.
The tomb was built in the early Tang Dynasty (618-907), Zhu said.