Construct a HistoryFantasy novel writers work out a history as they build a fantasy world. This involves anything from politics, religious views, and anything similar that may divide or bring people together.
Books with pictures stimulate world-building ideas. Encyclopedias for older children present one potential source. Flip through the pages and glance at the pictures. When you find an item or event that stimulates your imagination, consider it. Text included in this type of book is short enough to peruse information in minutes. From there you can either research it further, use what you've learned or dismiss it entirely. The bottom line is that it doesn't waste a lot of time.
Don't allow character or plot to sidetrack from the task of pulling together geographical details; jot down exciting but distracting ideas to get them out of your head and into a safe place until the basic world has evolved enough for characters to walk about. If your story takes place in a specific city investigate the history of that city. Even when writing fiction you need to use enough facts to make the story believable.
Once the landscape is in place, add characters and build a rough timeline. The past and future don't need to be well defined, but exist enough to help the fantasy writer know where characters came from and where they are going.