Red Eagle Entertainment secured the screen rights to The Wheel of Time in 2004, in a deal with novelist Robert Jordan (who passed away in 2007). Red Eagle spent eleven years developing film and TV projects based on the novels with multiple partners, including Warner Brothers and later Chris Morgan (The Fast and the Furious franchise) at Universal Studios, to no avail. In 2014 Red Eagle teamed with the experienced Radar Pictures to develop a television pitch for Sony. This deal was deep in negotiation when Red Eagle's time limitation on the rights expired in 2015; to keep the rights they developed a self-funded short film called The Winter Dragon. This led to a brief legal case, after which Red Eagle and Radar Pictures retained the screen rights to the franchise. In 2016 the TV rights to the novels were sub-licensed to Sony. Sony partnered with Amazon in 2017 to bring the novels to television, with production beginning in 2019. It is this project, led by Rafe Judkins, which is expected to hit the screens in a few months and has just started shooting its second season.
However, Red Eagle and Radar have retained the ability to develop other parts of the franchise. A few years ago this would have been meaningless - the fifteen Wheel of Time novels (the fourteen main books and the New Spring prequel volume) are the main appeal, obviously - but we've seen an explosion of screen projects based on notes, outlines and thin or non-existent source material in recent times. Both Amazon Television's new Lord of the Rings TV series, set in the Second Age of Middle-earth's history, and Warner Brothers' War of the Rohirrim animated film are based on notes and outlines left behind by J.R.R. Tolkien rather than actual novels. HBO's House of the Dragon TV series is based on a couple of chapters in George R.R. Martin's "fake history" of Westeros and Essos, Fire and Blood, rather than a full novel (though they have the benefit of being able to call on Martin for advice), and several other spin-off projects in development are based on even less. Netflix has developed a Witcher animated film and a full prequel mini-series which they've had to create from scratch (though again they've been able to enlist novelist Andrzej Sapkowski as a consultant). Sony and Amazon are probably kicking themselves at not securing the full screen rights to the franchise at an earlier date.
The movie trilogy appears to be adapting the primary backstory event in the history of the novels: the War of the Shadow. The books depict the Age of Legends as a time of peace and prosperity with humanity using the One Power - a highly regimented form of sorcery - to create a utopia of equality and prosperity. However, an experiment into using the Power goes awry, letting a force of profound evil enter the world. Society gradually collapses over the course of a century, leading into a devastating global war which kills billions. Eventually, under the leadership of Lews Therin Telamon, the man nicknamed "The Dragon," humanity is victorious and seals the source of evil away again, but at the moment of triumph the male half of the One Power is corrupted, sending every male channeller (magic-user) insane on the instant, devastating the world in their madness. The female-led Aes Sedai emerge in the aftermath of this chaos to restore order to the world. The events of the Wheel of Time novel series take place some 3,400 years later, by which time humanity has managed to drag itself back to a semi-Renaissance level of technology and development, but the return of the "Dragon Reborn" (Lews Therin's reincarnation) and a renewed War of the Shadow looms large over the world.
Screenwriter Zack Stentz has some reasonable form, co-writing the screenplays to Thor and X-Men: First Class (both in 2011), as well as co-writing Agent Cody Banks and writing Netflix's Rim of the World. He has also written multiple episodes of Andromeda, Terminator: The Sarah Connor Chronicles, Fringe, The Flash and Jurassic World: Camp Cretaceous.
So far the project is only in development; Radar will have to find a major studio partner to provide the immense budget such as project would need, and that might only be viable once the TV show debuts and if it is a success.