The Thurian Age is a specific epoch in the fictional timeline used by Robert E. Howard in his Kull stories. It predates the Hyborian Age of the Conan the Barbarian stories and is known to them as the Pre-Cataclysmic Age. The main continent is called Thuria, although smaller continents such as Atlantis and an unnamed Eastern continent exist, as do several island chains. Most of the planet is unexplored wilderness inhabited by "scattered clans and tribes of primitive savages." The boundary between the two ages is marked by the "Great Cataclysm," which might have taken place as early as ca. 35,000 to 40,000 B.C, or as recently as 18,000 B.C. depending on the sources considered. When Robert E. Howard began to chronicle the adventures of Conan the Cimmerian, more than seventy years ago, he prepared a fictional history of the Hyborian Age which he had created. That "history" dealt not only with the period during and after Conan's life, but also with events some eight thousand years earlier, during the Thurian civilization which produced King Kull, exiled warrior of Atlantis in the days before that continent sank into the surging seas.
A great cataclysm ends the Thurian Age some time after the Kull stories. Several countries sink into the sea, others rise from it, and the rest is devastated by earthquakes and volcanoes. Civilization is destroyed and the survivors attempt to build a new culture but warfare and a Lesser Cataclysm strike, creating the Hyborian Vilayet Sea and destroying any last remnants of Thurian society.
Six kingdoms dominate the main continent of Thuria. All share a common language and possibly a common origin. East of these kingdoms is a vast desert. The six kingdoms are all part of the "Seven Empires" although the seventh member is never named.
Following the Cataclysm, one of the kingdoms (not Valusia), become the Zhemri people who eventually form the land of Zamora (the people of which in turn eventually become the Romani people).
They are described as having wars with Valusia but it does not appear in the Kull stories.
The kingdom furthest to the east of the Thurian continent, bordering the eastern desert. Its people are less cultured than those of the other kingdoms.
In an untitled draft in Kull- Exile of Atlantis, Grondar is 1) described as being east of Zarfhaana and having a wasteland, 2) occasionally sending out raiders into the grass savannah that separates it from its western neighbors, 3) Thurania is a named target of these raids, 4) the ancestors of the Grondarans came from somewhere unknown and defeated an older people who inhabited the land now known as Grondar (the remains of the original inhabitants' cities lie in the grass savanah between Grondar and the western kingdoms), and 5) hinted that Grondar didn't have cities similar to those of the west.