Most of the Hyborian Age is dominated by civilizations in the west of what remains of the continent of Thuria, destroyed in a Great Cataclysm that shook the world 30,000 to 35,000 years ago, breaking up Thuria and casting Atlantis and the remnants of Lemuria and Mu under the waves, sparking the eventual dawn of the Hyborian Age.
After several thousand years (about 17,0000 years ago) the leftover savage tribes of the Thurian Age slowly reformed into a host of new kingdoms. Around these lie the farther and more exotic kingdoms of the Northern Barbarians, the Eastern tribes, and the far Southern kingdom of Stygia. The age would last until about 9,500 years ago when the world is cast into a new Dark Age with the fall of Aquilonian civilization, paving the way for modern history.
The main Hyborian kingdoms are:
Combinations of these and the outer Kingdoms formed the basis for the historical human races after the glacial ages forced changes in the society and geography of the world.
Around these Western Kingdoms sit several outer Kingdoms nearby or separated from them by inhospitable lands.
To the East:
To the South East
Far to the South:
To the North are several barbarian societies, loosely forming kingdoms and tribes.
The Hyborian Age has a long history of conquests and wars between its multitude of kingdoms. As it was forming the Aquilonian kingdom formed the most powerful region. Later Pictish unity overthrew Aquilonia while an invasion from the far Eastern kingdom of Hyrkania split the western kingdoms.
The Picts and Hyrkanians formed two massive empires facing each other leading to a period of relative peaceful development if not actual peace. This was changed when an invasion came from the less civilized Aesir.
Around this time the migration of the glaciers began forcing drastic changes and the Hyborian Age began its slide into myth.
The Atlantean continent's western regions sink, leaving only the islands that become Bal-Sagoth and Poseidonis. (??western; "The Gods of Bal-Sagoth," Howard; Poseidonis??)
The last Atlanteans, who flee northward, become the barbaric Cimmerians. The surviving Lemurians are enslaved by an unknown ancient race in the eastern part of the Thurian continent.
Mu rises again, and Ghatanothoa summons his servitors, the lloigor. The lloigor enslave the humans who came to live on the newly risen land. ("The Return of the Lloigor," Wilson; ??YEAR THIS SOURCE SAYS B/T 20,000 AND 12,000)
Bokrug and the Thuum'ha come to Earth and found the kingdoms of Ib in the Middle East and Lh-yib in the land of the Cimmerians.
c. 17,500 BC: A lesser cataclysm breaks the Thurian continent in two.
c. 15,500 BC: In the eastern part of the shattered Thurian continent, the Lemurians free themselves from slavery. The Lemurians travel west and overwhelm the serpent people there, founding the kingdoms of Acheron and Stygia. They adopt the practices of the serpent people and worship many dark gods, including Nyarlat, Sebek, Set, Gol-Goroth, and Shuddam-El. The Stygians also cultivate a plant called the Black Lotus, which "enhanced" their worship of their deities. ("The Hyborian Age," Howard; "Timeline of the Cthulhu Mythos," Appel; "The Children of Yig," Appel; "Dope War of the Black Tong," Price)
The surviving serpent people flee to the southern edge of the continent. ("The Children of Yig," Appel)
c. 15,000 BC: The Cimmerians, under the chieftain Crom-Ya, begin their ascent to glory. Crom-Ya is later deified as the god Crom. ("The Shadow Out of Time," Lovecraft)
c. 13,000 BC: The Hyborians, a northern people, conquer Acheron and form eight separate countries- Aquilonia, Argos, Brythunia, Corinthia, Koth, Nemedia, Ophir, and Zingara. Stygia, however, endures. ("The Hyborian Age," Howard; "Black Eons," Howard and Price)
The oldest copies of the R'lyeh Text, written on scrolls in a Chinese-esque language, date from at least this time, although they are probably older. (Ex Libris Miskatonici, Stanley)
c. 10,000 BC: The time of Conan. The Cimmerian barbarian wipes out the last serpent people in their Hyborian city of Yanyoga. ("Timeline of the Mythos," Appel; "The Children of Yig," Appel)
c. 9600 BC: The Hyborian Age begins to end, as the nations and peoples of the era begin to fight. Aquilonia and Hyperborea battle, the Picts and Hyrkanians wreak havoc across the land, and the Vanir destroy Stygia. The Aesir settle in Nemedia, and the Cimmerians war against the Hyrkanians before retreating to the east. The Hyborians themselves are overwhelmed by another northern people. This is the time of the heroic Ghor Kin-Slayer of the Aesir, and the warlord Gorm of the Picts. ("The Hyborian Age," Howard; "Black Eons," Howard and Price)
c. 9550 BC: A final cataclysm destroys the Hyborian world and rises new land masses, moving the world into more or less its modern configuration. Portions of the Hyborian continent, Poseidonis, and Mu all sink beneath the waves. In later times, this event is remembered as the Great Flood. ("The Hyborian Age," Howard; "Timeline of the Cthulhu Mythos," Appel)