Aaron left the area after he got the necklace. There was nothing else to gain anyway at that place. Moreover, with him taking away the necklace, the mist started to thin little by little.
This would certainly attract attention from everyone, not just the alliance but also the cults.
The appearance of any mysterious occurrence can be attributed to the presence of something powerful, like treasures or even some powerful creatures.
How its appearance attracts people, so would its sudden disappearance. People would want to know why this anomaly suddenly disappeared.
If the anomaly was caused by some treasure, they want to know who obtained the treasure, and maybe be can get the treasure from them. If the anomaly was caused by the presence of a powerful creature, the people want to know why it suddenly disappeared from the area.
If a powerful creature disappeared from its resting area would be for very few reasons.
One is that it found something interesting and moved to get that.
