Withered Heath.

In the Eastern Ered Mithrin the mountain range divided into two spurs, a Northern and a Southern but both extending East. Between the two spurs was Withered Heath. The name derives from the fact that in this area bred and lived Dragons. The area had an approximate size of North-South 40 Miles, East-West 150 Miles. In the Third age Thorin I. removed from Erebor and the Lonely Mountain to the Far North ( This was the mountains Ered Mithrin. ) and established a dwarf-dwelling there with most of his kin but Dragons arose and plundered their works and wealth and many of the Dwarves fleed back South and at last his great-grand Thror son returned to Erebor. There can hardly be any doubt that Smaug the Golden came from Withered Heath.