As fans are still reeling from the finale of HBO’s “Game of Thrones,” the network has quietly begun production on the first prequel series set in the world of Westeros.

Prior to the flagship fantasy drama ending, the network revealed that it had been working on a slew of spinoff content since 2017, having tapped five writers to pen potential projects. Of those five, only one from Jane Goldman (“Kingsman: The Secret Service” and “X-Men: First Class”) has been given a pilot order.

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According to Entertainment Weekly, the prequel pilot began filming in Northern Ireland, which served as the production hub of the “Game of Thrones” during its run. In addition to Goldman acting as showrunner, author George R.R. Martin as well as “Thrones” creators Dan Weiss and David Benioff will executive produce. S.J. Clarkson (“Jessica Jones”) will direct.

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The story from Goldman is reportedly set thousands of years before the events of “Game of Thrones” and chronicles the world’s descent from the Golden Age of Heroes to the rise of the White Walkers and the near-destruction of man. On his blog, Martin, who helped develop the prequel, unofficially refers to the series as “The Long Night.”

“Westeros is a very different place,” Martin told EW. “There’s no King’s Landing. There’s no Iron Throne. There are no Targaryens — Valyria has hardly begun to rise yet with its dragons and the great empire that it built. We’re dealing with a different and older world and hopefully that will be part of the fun of the series.”

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Precious little else is known about the prequel pilot, which has not yet been picked up to series. Naomi Watts will star along with Naomi Ackie, Denise Gough, Miranda Richardson, Josh Whitehouse, Jamie Campbell Bower, Sheila Atim, Ivanno Jeremiah, Alex Sharp and Toby Regbo.