The Ourean Cordillera

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It serves as the backbone of the Oureas, formed through the pushing of multiple tectonic plates against each other. 

This results in:

North Ourea: The Roman Plate spins in the same spot, creating a vast, elliptical series of mountain ranges when other plates collide with it. It travels Northeast, forming the Numa river valley and Drake River plateau.

South Ourea: The Pontian Plate, occupying the southern section of Pontian Ocean Basin, is directly responsible for geological activity in Southeastern Marea, Garmea, and South Ourea. As it moves eastward towards the Roman Plate and Naimane Plate, it forms long ridges of low lying mountains until it reaches mainland South Ourea. There, the combined forces of the Pontian, Naimane, and Garsorann Plates force up some of the tallest mountains on Annora. 

It is still debated as to whether this same mountain range is connected to the West Annoran Cordillera, a series of mountains stretching from the Garmean Archipelago to Garsor.