George R.R. Martin has posted an excerpt from his upcoming companion book to his bestselling Song of Ice and Fire novels. On the author’s website , he released an entry from The World of Ice and Fire: The Untold History of Westeros and the World of Game of Thrones. The book is mega encyclopedia covering the events and historical figures that shaped the Seven Kingdoms and beyond.

The excerpt gives some background for fans of Daenerys Targaryen, setting the stage for the dragon-aided conquest of Westeros by her ancestor Aegon I Targaryen. But also intriguing is the accompanying illustration, which shows Aegon atop his dragon Balerion the Black Dread. Martin confirmed to EW the image accurately represents his vision for what a fully grown dragon will look like — can you imagine Dany riding one of these? (on Thrones, we’ve seen an adult dragon’s skull in season one, but the living dragons on the show are still adolescents). The book is released in October. Check out Martin’s sample.