In Genshin Impact, after assisting Bona in purifying the Abyssal Corruption from the Chu'ulel Light Core, players must help her locate the Primal of Flame. Once found, Travelers must offer two Pyrophosphorites (obtained during the Palace of the Vision Serpent Quest) to the Altar of Primal of Flame. This offering unlocks access to Tonatiuh, a floating island above Ochkanatlan’s Cradle of Fleeting Dreams. Reaching Tonatiuh completes the To the Sky-Road Quest and begins The Other Side of the Sky Quest, requiring the collection of four Burning Firestones to acquire the Jade of Return.

How to Obtain the Four Burning Firestones

Burning Firestone #1

The first Burning Firestone is obtained by:

1. Reaching Tonatiuh.
2. Waiting for the cutscene with Bona to conclude; the Little One will retrieve the first Firestone.
3. Following the Little One to the bridge, activating the nearby mechanism to raise the lift.
4. Interacting with the small Saurian and Bona.
5. Watching another cutscene.

Burning Firestone #2

The second Burning Firestone is located on the northeastern isle. To obtain it:

1. Rotate the right and left floating isle mechanisms.
2. Cross the extended bridge eastward.
3. Raise the lift and follow the Little One to the Firestone.
4. Collect a Common chest along the path.
5. Activate the mechanism to the right of the Firestone, climbing the resulting platforms.
6. Defeat the enemy and collect an Exquisite chest atop the tower.
7. Activate the mechanism behind the chest to open the gate.
8. Descend to the small Saurian, open the locked door, and tell the Little One "Let’s return to the altar!"
9. Return to the Altar of Primal of Flame.

Burning Firestone #3

To acquire the third Burning Firestone:

1. Rotate the right and northern floating isle mechanisms.
2. Cross the bridge to the northern isle's lower level and follow the Little One.
3. Observe a Secret Source Sentinel carrying the Firestone to the southwestern isle.
4. Proceed to the northwestern edge, inhabit a Qucusaurus, and fly towards the Pyroculus.
5. Activate the tower mechanism, transform into a Qucusaurus, and fly to the unlocked door.
6. Use the elevator to return to the upper level, interact with the small Saurian, follow it, activate the lift, and return to the Altar of Primal of Flame.

Burning Firestone #4

The final Burning Firestone is on the northwestern isle's upper level:

1. Cross the northwestern bridge, requesting Bona to tilt it upwards.
2. Glide to the northern isle's upper level.
3. Lower the lift and follow the Little One.
4. Instruct the Little One to return to the altar.
5. Defeat the enemies, and again tell the Saurian to return to the altar.
6. Collect a Precious chest and proceed to the Altar of Primal of Flame.

Offering all four Firestones to the Altar completes The Flowing Primal Flame Quest, triggering a cutscene transforming the Jade of Return into a Golden Entreaty. The Dragon of the City of Flowing Ash then appears, leading to The Other Side of the Sky Quest on the Nursery of Nightmares island, rewarding 50 Primogems.