Most often people think of Transylvania as having a huge tourism industry, after all they have so many historical castles and cities, many of which are still lived in.
Natural resources is still a important aspect in Transylvania. There have been mines and other industries, such as forestry for centuries, all of which are natural resources. It is this part of the land that most do not take into consideration. The mountains, will hold more resources, and there is always the potential for these to be mined or more oil being found.
Still, the more Transylvania, and Romania focuses on tourism and technology the less important the natural resources will be. That is the cycle of history-- which Transylvania has a lot of.