The Gaean Reach is the setting of an informal grouping of a number of science fiction

Science fiction

Science fiction is a genre of fiction dealing with imaginary but more or less plausible content such as future settings, futuristic science and technology, space travel, aliens, and paranormal abilities...

 books by author Jack Vance

Jack Vance

John Holbrook Vance is an American mystery, fantasy and science fiction author. Most of his work has been published under the name Jack Vance. Vance has published 11 mysteries as John Holbrook Vance and 3 as Ellery Queen...

 (who has never categorized his books in such a manner).

The Gaean Reach consists of all worlds colonized by humans, among which trade and travel flow freely for the most part. Some of these worlds are advanced and cosmopolitan, such as Alphanor; others, like Thamber, are inhabited by shipwrecked and forgotten people, who have reverted to feudalism

Feudalism

Feudalism was a set of legal and military customs in medieval Europe that flourished between the 9th and 15th centuries, which, broadly defined, was a system for ordering society around relationships derived from the holding of land in exchange for service or labour.Although derived from the...

. Some, like Wyst

Wyst: Alastor 1716

Wyst: Alastor 1716 is a science fiction novel by Jack Vance first published by DAW Books. It is the third and last novel set in the Alastor Cluster, a vast section of stars and planets ruled by the mysterious Connatic, which may or may not be a part of Vance’s Gaean Reach.-Setting:Arrabus on the...

, are undeniably strange in their culture and customs.

The period of the Gaean Reach spans several centuries, if not millennia, at an indeterminate time in the future. Specific dates are given in the early books of the Demon Princes

Demon Princes

The Demon Princes is a five-book series of science fiction novels by Jack Vance, which cumulatively relate the story of one Kirth Gersen as he exacts his revenge on five notorious criminals, collectively known as the Demon Princes, who carried his village off into slavery during his childhood...

 series, but not in the others. The human civilization in the Demon Princes is the Oikumene, which can be seen as a precursor or variant to the Gaean Reach. The Reach is mentioned in the three Alastor books, the Cadwal Chronicles

Cadwal Chronicles

The Cadwal Chronicles are a trilogy of science fiction novels by Jack Vance set in his Gaean Reach fictional universe. The three novels are called Araminta Station, Ecce and Old Earth and Throy.- Storyline :...

, Ports of Call

Ports of Call

Ports of Call is a science fiction adventure novel by Jack Vance, the first of a duology along with its sequel Lurulu. It follows a young man named Myron Tany on a picaresque journey through the Gaean Reach.-Plot summary:...

and Lurulu

Lurulu

Lurulu is a science fiction adventure novel by Jack Vance, the second of a duology along with its prequel Ports of Call. It continues to follow Myron Tany on a picaresque journey through the Gaean Reach....

. Singleton works are also included, such as Emphyrio

Emphyrio

Emphyrio is a science fiction adventure novel written by Jack Vance. It tells the story of a young man who overturns the foundations of his world.- Plot summary :...

, Night Lamp

Night Lamp

Night Lamp is a science fiction adventure novel by Jack Vance. It follows an orphan named Jaro Fath on his quest to learn where he came from.-Plot summary:...

, and possibly The Gray Prince

The Gray Prince

The Gray Prince is a science fiction novel by Jack Vance.The overarching theme of the work is the morals of possession of land.- Setting :...

.