The thaig was built upon Cad'halash, an ancient settlement which at one point became a sanctuary for elven refugees from Arlathan. When this was discovered by the dwarves of Kal-Sharok, they destroyed the thaig in order to cover the evidence and not jeopardize their alliance with Tevinter Imperium.
The thaig was rebuilt and, briefly, repopulated. The Shaperate also conducted a significant excavation and research on discovering more about the lost Cad'halash settlement which created controversy on whether it should be added into the Memories or remain forgotten. At some point a huge stone statue was also erected on the highest hill to honor those who had sacrificed their lives to become golems.
Cadash was eventually overrun with darkspawn and deepstalkers, however. Driving the populace out once more.