Thunderbeast tribe was a group of Uthgardt.
1370 DR, their chief was the charismatic Gundar Brontoskin, but he was replaced around 1372 DR by Sungar Wolfkiller. Late in the 15th century, the tribe arrived at Morgur's Mound for Runemeet to find it disinterred, missing the skeletons of the Thunderbeast and Morgur as well as the treasure buried within. Since they could no longer practice their traditions there, their current chieftain, Grandthur, decided that the Thunderbeast would meet the Elk tribe at Flintrock. He left a guard to wait for the Gray Wolf tribe to return to Neverwinter Wood and ask them what had happened.
Their ritual enemies were
wolves. They were known as the least barbaric of the Uthgardt, although they still did not practice agriculture.  They guarded the secret that  thunderbeasts still lived deep in the High Forest.
The Thunderbeast's ancestor mound was
Morgur's Mound, but they lived in the High Forest area. 
slade (April 1996). , The North: Guide to the Savage Frontier p. 19. TSR, Inc. ISBN 0-7869-0391-0.
2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7
Matt Sernett, Erik Scott de Bie, Ari Marmell (2011). , Neverwinter Campaign Setting p. 30. Wizards of the Coast. ISBN 0-7869-5814-6.
Brian R. James and Ed Greenwood (September, 2007). , The Grand History of the Realms p. 63. Wizards of the Coast. ISBN 978-0-7869-4731-7.
↑ 4.0 4.1 4.2 4.3 4.4
Ed Greenwood, Sean K. Reynolds, Skip Williams, Rob Heinsoo (June 2001). , Forgotten Realms Campaign Setting 3rd edition p. 168. Wizards of the Coast. ISBN 0-7869-1836-5.