Blood Sacrifice
After building Roshani a hut, enter it and get another mission from him. You will find him worrying about an abducted Wenja and the captors saw him in your village.
Tensay comes in and demands Roshani to tell you the reason. You find out it is for sacrifice. You must go and stop them from sacrificing your tribesman.
Head over to the map marker again, around the southern portion of the map.
As you approach the area, you will notice it looks very similar to the Stonehenge in real life.
You will find some Izila dancing around the sacrifice. There are other Izila around. Deal with them however you please.
The priestess is late so if you managed to kill all the Izila fairly quickly, she might arrive without a clue. She will be marked in red in hunter vision.
After all the reinforcements are dead, free the Wenja to finish the mission.