The Thunderfields are the Grasslands between the Wormpass and Elfpass Mountains. There are so named for the Storms that coming booming over the Northern Elfpasses during MidDay.  The rain is strictly Seasonal - most of the rest of the year is dry.

The northern grassland, which the Centaurs call DragonsCrypt with some justification, is a shortgrass pairie that is exceptionally dry and prone to fires (especially Dragonfire). The southern area is tallgrass pairies and much wetter, with a few actual Rivers.

In addition to Centaurs and Dragons, there are Diggers under the Grasses, and graceful herds of Magical Irisbix, which are hunted by the noble, if savage, Lion Celenes.