The US network announced that they have ordered a pilot for the show which will act as a prequel to the flagship series which is currently in the middle of production for its final season.

The untitled series will take place thousands of years before the events of 'Game Of Thrones' long before the battle for the Iron Throne.

The new series will be written by author of the novels George R.R Martin and British screenwriter Jane Goldman.

Goldman is known for her collaborations with director Matthew Vaughan on films like 'Kingsman', 'Kingsman: The Golden Circle' and 'X-Men: First Class.'

HBO said in a statement: "Taking place thousands of years before the events of Game of Thrones, the series chronicles the world's descent from the golden Age of Heroes into its darkest hour.”

"And only one thing is for sure: from the horrifying secrets of Westeros's history to the true origin of the White Walkers, the mysteries of the East, to the Starks of legend … it's not the story we think we know."

It is believed that the new series will not be broadcast until the eighth and final series of 'Game Of Thrones' airs in 2019.