An area of flat or rolling land at high elevation is called a plateau.

Here are some other terms that might apply depending on the specific features of the land:

* Tableland: A plateau with a flat, table-like surface.

* Mesa: A plateau with a flat top and steep sides, often smaller than a plateau.

* High plain: A plateau with a relatively smooth surface, often found at high elevations.

* Meseta: A plateau, specifically in Spain.

Let me know if you'd like more information about these terms!