You can blame Tolkien for these. After I had finished reading Lord of the Rings, I read (and re-read) the indexes, which were full of fascinating details on the languages, both Elvish and Dwarvish, timelines of events and the inevitable maps. After a while, I developed the habit of creating my own timelines, drawing my own maps, making up my own worlds, although (to date) I have never created my own language.