Six Directions of Space is a limited edition novella written by Alastair Reynolds. There were 1000 copies printed (my signed copy is somewhere in the 400’s), though, like other Reynolds stories that appear in limited edition collections (such as Zima Blue) Six Directions of Space will probably turn up in a later Reynolds compilation (it also appears in the collection Galactic Empires (linked below) with stories by Peter F Hamilton, Ian McDonald and Neal Asher). This alt-history story primarily revolves around a space-faring Mongol culture that was not wiped out during the invasion of Japan in 1274. The empire has found a series of hyperspace conduits, called the Infrastructure, which allow it to build an empire spanning several thousand light years by the equivalent of our 23rd century. The infrastructure was built by a long since extinct race and is starting to decay. This decay causes the mystery that is central to Six Directions of Space which is that the Mongol Empire has charted most of the Milky Way and found no other active intelligent races, yet from time to time ships travelling through infrastructure conduits encounter starships that are both alien and familiar.
What I liked about this novella is the density of complex ideas covered in a very short amount of space. Reynolds manages to build an interesting universe and present an interesting mystery in a very short amount of time. Given that he has gone back to other universes that he’s created in this fashion (House of Suns evolved from a similar shorter fiction effort), I’d be enthusiastic about him returning to the one explored in Six Directions of Space.
This story has also been reproduced in the collection Galactic Empires with other authors I love like Hamilton and McDonald – so you might prefer to get that collection as a way of picking up this story (if you can find it).