To enter Goldenhills Valley, you need to have focused on the main quests in Silverglade, as well as the following quests:
- Mysteries of the Circus
- The Meeting in Sacred Grove
If you still have not unlocked Goldenhills Valley after following these steps, it likely means you need to do some more main quests.
Keep your eyes open for “The Key is Ready”; this quest will let you open the gates.