Here is the full list of all 13 Light of Alariya achievements.
Complete the Temple in the Red Sands
Complete the Temple in the Yellow Sands
Find a scrap of the shattered prophecy
Reach to top of one observatory
Hear one of Ari's stories about her journey
Receive a gift
Find a piece of literature that was left behind
Complete the Temple in the Black Sands
Return to Alariya and save your people
Find all pieces of the shattered prophecy
Reach the top of three observatories
Hear all of Ari's stories about her journey
Find 12 pieces of literature left behind