There is a nearly uncountable number of stars in the milky way, and there are many in between the major star systems that either have a minor presence in the form of small outposts or are entirely uninhabited and uninteresting.
The paths between systems are not always similar in length, but generally require between 2 and 3 weeks for ships to travel between depending on interstellar conditions and FTL mechanism employed.
It is about 70 ly between star systems like Sol and Atlantica. This means there could be between 5700 and 8500 star systems between Sol and the first layer of interesting star systems listed on the map. These star systems have largely been ignored because they lack habitable planets and/or lack any of the exotic materials needed for SLE construction.