To get this quest, go to the teleport waypoint in Lingju Pass, and glide down further into the ruins.
Investigate the strange camp
Look for 3 points of interest in the area. They are not far from each other, so it's pretty easy to find.
Look for the missing scholar
You will then be asked to find the missing scholar. There are a lot of enemies and things that you can do in the ruins, so you can explore to get some treasure. But most of it is not necessary for the quest. If you just want to continue, head to the upper left part of the area, near the waterfalls. You can climb there using a statue near the broken bridge and jump to the left.
Defeat the Treasure Hoarders and obtain the key
Once you reach the upper part of the ruins, you will find some treasure hoarders that you need to clear out. Then get the key from the treasure chest near the cage and free the scholar.
Collect the treasure
Once you talk to the scholar, she will tell you the location of the treasure, which is hidden near a giant tree in Lingju Pass. Simply head back to the middle of the ruins and go near the tree as shown in the picture above, a prompt will appear for you to "dig" and get the treasure.