You can fly to the Forbidden Reach on your dragon anytime you like by simply flying across using Dragonriding, aim to the north of The Waking Shores. However it’s worth noting you will not have access to quests until you do the prerequisite quests.
First of all to get to the Forbidden Reach you will need to complete a short series of quests, starting at the Seat of the Aspects in Valdrakken:
- Hidden Legacies
- Return to the Reach – Officially sent to the Forbidden Reach for the first time
- An Eclectic Accord, Stemming the Irontide and Wings of Mercy – Unlocks Envoy and World Quests in the Forbidden Reach.
After this, you will have unlocked all the quests in the Forbidden Reach, completing further quests will lead to you unlocking different systems within the Forbidden Reach.