The Six Directions of Space — Alastair Reynolds

What if Genghis Khan got his wish, and brought the entire planet under the control of the Mongols? Where would he have gone next?

A thousand years after Khan's death, Yellow Dog is the codename of a female spy working for a vast Mongol-dominated galactic empire. When she learns of anomalous events happening on the edge of civilised space -- phantom ships appearing in the faster-than-light transit system which binds the empire together -- Yellow Dog puts herself forward for the most hazardous assignment of her career. In deep cover, she must penetrate the autonomous zone where the anomalies are most frequent, and determine whether the empire is really under attack, and if so by who or what. Yellow Dog's problems, however, are only just beginning. For the autonomous zone is under the heel of Qilian, a thuggish local tyrant with no love for central government and a reputation for extreme brutality. Qilian already knows more about the anomalies than Yellow Dog does. If she is going to learn more, she will have to earn his confidence -- even if that means working for him, rather than against him.

So begins a deadly game of subterfuge and double-cross -- while the anomalies increase...