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"The Ghosthead came here from the universe’s eastern rim. They passed the rock globes that circulate in the sky-another, more evanescent kind of world than ours on the infinite plateau-and came here, to a land so mild it must have seemed like balm: an endless, gentle midmorning. And its rules were not theirs. Its nature was debatable."
Uther Doul on the arrival of the Ghosthead empire

See Also: Ghosthead

The Ghosthead Empire was a civilization of extraplanar entities, the eponymous Ghosthead, that ruled over Bas-Lag around 3,000 years prior to the events of Perdido Street Station. Much about the Empire has become shrouded in myth, owing in large part to their use of Possibility science in daily life.


The Ghosthead Empire was founded by the arrival of the Ghosthead in an area now known as the Fractured Land, although the devastation extends through an area of the sea thousands of miles away, called The Scar. The empire rule for around 500 years, until a rebellion known as the Contumacy overthrew them, followed after by a period of time known as the Sloughing-Off.

Period of Rule[]

Ghosthead rule was marked by extensive use of Possibility theory. Musical instruments made use of Possibility, with concerts defined by possible notes that faded into and out of existence alongside factual notes. One sport at this time was Possible Wrestling described as "a shifting multitude of limbs flickering in and out of existence, nigh grappling nigh grappling fact grappling nigh again".

The Cactacae first appeared during Ghosthead rule, although the correlation between their appearance and the use of Possibility by the Ghosthead remains ambiguious.


The Ghosthead Empire clashed with the Khepri empires of ancient Bered Kai Nev, which were able to throw vast numbers of soldiers against the Ghosthead and their forces. This conflict by itself did not pose an existential threat to the Ghosthead Empire.

The Ghosthead rule began to come to an end with the slow-building revolt known as the Contumacy.

The Contumacy[]

See Also: Sloughing-Off

The Contumacy was a centuries-long revolt against the Ghosthead. In its initial stages, the revolt took the form of attacks against Ghosthead institutions, representatives, and devices. As the revolt turned into outright rebellion, known as the Sloughing-Off, cities and towns simply vanished in "thought cleansing" operations, while others learned methods to kill and drive out the Ghosthead without raising armies. Records of the Sloughing-Off describe a Ghosthead retreat back to their homeland in the wake of the successful rebellion.

Although the exact nature of the revolt is unclear, records speak of "possibility fraud" and "demonstration devices", implying that machines were used to diminish Ghosthead ability to mine the favorable probabilities that supported their rule.

Possibility Technology[]

See also: Possibility

Owing in part to the incredibly harsh conditions of their homeland, the Ghosthead Empire made heavy use of Possibility Mining and its associated sciences. The cultivation and selection of favorable possibilities was a key part of Ghosthead governance, and also defined their art, music, architecture, and warfare. A scarce few of their artifacts have survived, including at least one Possible Tower, a Perhapsadian, and Uther Doul's Possible Sword.


  • The Ghosthead Empire is first mentioned in The Scar.