In House of Chains
According to L'oric, the Elder Warren of Kurald Thyrllan had been born of violence, the shattering of Darkness. The shattering of its sister warren had left Kurald Thyrllan twisted and fraught, and difficult to enter. The warren had ultimately branched off in many directions, first creating Tellann and later Thyr, the human warren of light. Telas, as a child of Tellann, likely had its roots in Kurald Thyrllan as well.
In Reaper's Gale
Beak observed that Stormy and Gesler were "reforged in the fires of Tellann". He then went on to say:" Telas, Kurald Liosan, the fires, the ones dragons fly through to gain immunities and other proofs against magic and worse".