Bas-Lag is the fictional world in which several of English author China Miéville's novels are set. Bas-Lag is a world where both magic (referred to as "thaumaturgy") and steampunk technology exist, and is home to many intelligent races. It is influenced by the themes and tropes of multiple genres of science fiction, fantasy, and horror.
So far there have been three novels set in Bas-Lag. They are:
Additionally, the short story "Jack", featured in the 2005 collection Looking for Jake, is a Bas-Lag story.
Bas-Lag possesses a number of continents. Two landmasses, Rohagi and Bered Kai Nev, are named in the three novels, though numerous other landmasses and unique structures play important roles in the novels.
The exact proportions and geography of Rohagi are unknown. New Crobuzon lies about ten miles (16 km) inland from its eastern coast, which borders the Swollen Ocean. Immediately south of New Crobuzon is the Rudewood, beyond which lies the Mendican Hills. North of New Crobuzon, along the coast but separated by the Bezhek Mountains, are the ruins of Suroch. To the west, about a thousand miles from New Crobuzon and far beyond the Dancing Shoe Mountains, lies the four-hundred mile wide freshwater lake called Cold Claw Loch. The Loch connects with the vast, inland Cold Claw Sea, eight hundred miles to the north, via a natural channel called Cold Claw Sound. The Cold Claw Sea is talon-shaped, stretching eastward a great distance, almost connecting with the Swollen Ocean before curving southward for about two hundred miles, finally ending about seven hundred miles north of New Crobuzon. This southward curve is the Gengris, and is populated by the dangerous and unpredictable grindylow.
According to a protagonist in Iron Council, both Cobsea and Myrshock lie about 750 miles (1,210 km) southwest of New Crobuzon. Cobsea lies inland and borders the Cacotopic Stain, a large created by the unreliable magical energy known as Torque. Myrshock lies on the northern coast of the Meagre Sea. As revealed in Iron Council, a wealthy industrialist had attempted to build a transcontinental railway that would link New Crobuzon with Cobsea and Myrshock, as the two states are trading partners, but was unsuccessful in this endeavor. However, the end of Iron Council indicates a second attempt at the project, using information gathered by the industrialist's agents throughout the course of the book.