The Bosnian pine (Pinus heldreichii) was dated by counting the rings, which are formed each year as the tree grows.
Paul J Krusic, the leader of the expedition that found the tree, described the its survival as "remarkable". Around the time that this tree was a seedling, in the year 941, the Vikings were roaming northern Europe. And it was already about 250 years old when the University of Oxford was founded.
"It is quite remarkable that this large, complex and impressive organism has survived so long in such an inhospitable environment, in a land that has been civilized for over 3,000 years," said Mr Krusic. This one was discovered by a team which included researchers from Stockholm University, the University of Mainz and the University of Arizona.
Studying old trees allows scientists to gain a better understanding of the history of climate change.
It is one of more than a dozen individual trees of around that age, living in a forest high in the Pindos mountains.