Quote Originally Posted by Blackhawk748 View Post
Its proven false about 5 minutes after we hear it and we know that they Jedi don't know a ton about the Sith or their practices and them having that level of cartographical information is downright unreasonable. It was a badly written line of dialogue that shouldn't be there because it causes issues like this, where you can't have Secret Planets or Systems because "The Jedi Archives hve all of it."
There's actually an elegant solution to the problems raised by this comment found in The Essential Atlas (actually there's a lot of elegant solutions to various problems in that book). Specifically, there's a difference between knowing where everything is and knowing how to get there. The former is simply a matter of astronomy. There's no reason why the Republic shouldn't have charted every star in the galaxy and all their planets. That's something you can do simply by building a suitably massive telescope array. You can discern the existence of planets around stars without ever actually seeing them, by detecting the gravitational effects. Happily, this is what Yoda actually tells Obi-Wan to do and it works immediately, as it should. However, actually getting to these places involves extremely complex charting of routes through another dimension known as hyperspace, whose interactions are only poorly understood. The Unknown Regions represent those areas of the galaxy (traditionally this was the 'western' side of the galactic disk, but it always included numerous nearly impossible to navigate pockets scattered everywhere) that no one had managed to chart yet. Note that this means the galaxy becomes less unknown over time as new locations are not only discovered, but routes to them are found. The Star Wars Rebels episode 'Legends of the Lasat' shows a (overly mystical) example of how this process can proceed when the crew charts a path through a stellar anomaly to discover the world of Lira San.

More broadly, there are plenty of planets in the Star Wars galaxy whose location may be 'known,' but are only tangentially connected to the rest of the galaxy. There are numerous examples of characters in canon material (and countless ones in legends) just stumbling onto some world that no one knows anything about which happens to be inhabited by some strange group of aliens or settlers with a complex history and is under some kind of threat. There are huge areas of the Outer Rim that are essentially 'wilderness' as far as the government is concerned, but just like wilderness areas beyond the frontier in 19th Century North America, that doesn't mean people weren't living there.