The Milky Way galaxy of Vernor Vinge's A Fire Upon the Deep is divided into 4 major concentric sections, known as "Zones of Thought":
The Unthinking Depths at the center of the galaxy, in which little or no intelligent life has evolved;
The Slow Zone, where the Earth exists. Intelligent life has evolved here but there is no true artificial intelligence and faster-than-light travel is not possible in this zone;
The Beyond, where intelligent species have mastered faster-than-light travel and and advanced civilizations have arisen;
The Transcend, the home of mysterious races of hyper-intelligent beings.
The intelligence that exists in these zones is not a coincidence - something about the physical properties of the zones prevent species and societies from evolving beyond a given allowable intelligence and technology.
In the novel, a group of humans have migrated from the Slow Zone to the Beyond-Transcend border, where they discover and accidentally awaken a dormant entity in the Beyond. The entity - known as the Blight - travels into the Beyond, destroying entire solar systems and threatens to destroy all life in the galaxy. Most of the story follows various inhabitants of the galaxy as they try to defend themselves and their worlds from the oncoming Blight.
The two factions have each adopted a human child - siblings whose parents were killed when they got in the way of a Tine battle.
I liked the universe that Vinge creates. He never explains why each zone restricts technology, but the fact that it does explains why species and societies evolve as they do within each zone.
I like the creatures with which he populates his universe, especially the Tines - a sentient, but primitive race that resemble long-necked dogs and group together in small packs that share a single consciousness; and the Skroderiders - a plantlike species that are able to travel thanks to a special cart built for them millennia ago by an unknown benefactor.
And I liked the contrast between the civil war waging on the Tines' world to gain mastery over a small bit of land and the oncoming Blight, which destroyed everything in its path and headed toward that same world.
But I found it difficult to sympathize or identify with Vinge's characters or their trials as much as I wanted to. Reading the story, I learned of death and love and trust and betrayal and they passed over me without moving me.
A Fire Upon the Deep was good for my head but it left my heart wanting more.