Telmor was a hidden draenei-populated city in Talador. It was built on a mountainside and was the closest draenei settlement to Auchindoun. The city was located in the middle of ogre country and made invisible by a protective spell using the Ata'mal crystal shard 
[Leafshadow]. Given Telmor's position at the southern end of the zone, it was presumably lost when Talador shattered and became Terokkar Forest.
Rise of the Horde
When Restalaan and his draenei party had rescued the young orcs Durotan and Orgrim who were under attack by an ogre, they were escorted to Telmor and Durotan memorized the incantation that deactivated the spell. Later, when the orcs started a war against the draenei, Durotan used this knowledge to remove the invisibility spell from Telmor, leaving the nearly undefended city open to attack. As a result, the city was taken over and completely destroyed, and Restalaan was killed.
After this, the city was offered to Durotan and his clan but he refused, so Blackhand and his Blackrock orcs gained control of the city.
Warlords of Draenor
Telmor has been attacked by the Shadow Council. Someone informed them how to disable the invisibility cloak maintained by [Leafshadow].[1] Restalaan took the fight to Vorpil Ribcleaver, but was wounded before an Adventurer came to his rescue.