The First Age, also known as The Age of Creation, is the first era of the history of RuneScape.
Very little is known about this age, as it ended roughly 8,000 years ago. The only things that can be safely assumed is this is the period when Guthix discovered a "blank plane" called Gielinor and shaped it how he pleased. A possible end of this age is when Guthix descended deep underground and began his long sleep until the end of the God Wars.
The Elder Dragons
An alternate theory proposed in the Book of folklore links the creation and 'lifeforce' of Gielinor with the existence of an ancient race of creatures known as the Elder Dragons. As long as the Elder Dragons remained the world would continue, though the extinction of the aforementioned dragons would result in the 'end of the world'. It is possible that the Elder Dragons could be the Dragonkin that Robert the Strong annihilated; however, the Dragonkin are believed to be extinct, though the survival of a very limited number would tie in with the Elder Dragons and the world's continued existence. However, the Elder Dragon theory is not widely known, nor popular with skeptic believing it to have been created to throw doubt on the idea of Gielinor being barren before the gods arrived.