In case anyone was wondering about the expansive, vast, universe in The Dispossessed, Le Guin has a (semi) serious explanation of the timeline of each book. They don’t all quite fit together, and really, why should they?
One of the things about Le Guin’s writing that I’ve always loved and appreciated has been her skill –– or ability, or creative fire –– to bring worlds to life. They appear to simply live, all of their own accord, and her writing presents them as anthropologist or historian might. They breathe, and when you upturn rocks there is life squirming in the dirt.
Anyhow. Here’s Le Guin in her own words about The Dispossessed’s place in the larger, starry night:
People write me nice letters asking what order they ought to read my science fiction books in — the ones that are called the Hainish or Ekumen cycle or saga or something. The thing is, they aren’t a cycle or a saga. They do not form a coherent history. There are some clear connections among them, yes, but also some extremely murky ones. And some great discontinuities (like, what happened to “mindspeech” after Left Hand of Darkness? Who knows? Ask God, and she may tell you she didn’t believe in it any more.)
OK, so, very roughly, then:
Rocannon’s World, Planet of Exile, City of Illusions: where they fit in the “Hainish cycle” is anybody’s guess, but I’d read them first because they were written first. In them there is a “League of Worlds,” but the Ekumen does not yet exist.
Then you could read The Word for World is Forest, The Left Hand of Darkness, The Dispossessed, in any order. In Dispossessed, the ansible gets invented; but they’re using it in Left Hand, which was written fifteen years earlier. Please do not try to explain this to me. I will not understand.
Then in the collection of stories A Fisherman of the Inland Sea, the three last stories are Ekumenical, and we even finally find out a little about Hain, where it all began. The story suite Four Ways to Forgiveness is part of that universe, and so is the novel The Telling. But I have to warn you that the planet Werel in Four Ways is not the planet Werel in Planet of Exile. In between novels, I forget planets. Sorry.
(From Le Guin’s FAQ)