The Ourea were the descendants of Gaea and the Protogenoi gods of mountains.
The Ourea, gods
of mountains

In Hesiod's Theogony, he explained the Ourea like this:

And she brought forth long hills, graceful haunts
of the goddess Nymphs who dwell amongst the glens of the hills.

The nine ourea were Aitna, Athos, Helikon, Kithairon, Nysos, Olympus, Oreios, Parnes, and Tmolus and they were the parthenogenetic offspring of Gaia alone.