I translated the entire Reasons of State timeline for the sake of reference:
***
In his novels and short stories, Andrzej Sapkowski often didn't pay much attention to the exact chronology of events, so the dates below are often only approximations. However, they do offer a cursory look at the history of the witcherverse. They were mostly established according to the seven books, the pen & paper role-playing game Wiedźmin - Gra Wyobraźni (The Witcher - A Game of Imagination) along with its expansions and materials available at www.sapkowki.pl
Distant past
The lands that will one day be roamed by Geralt of Rivia are first settled by gnomes and dwarves.
Later, 1000 years before humans, elves arrive on white ships and wage wars against the dwarves.
Ca. 746
The humans arrive - their First Landing takes place at the mouth of the Yaruga river and the Pontar delta. They begin the brutal conquest of the newly discovered lands, driving away the elves.
1062-1063
The elves, driven away to the east and unaccepting of coexistence with humans; take up arms under the lead of Aelirenn, also known as the White Rose. The insurgents suffer defeat, and there is a massacre of elven youth.
1161-1163
Falka's Rebellion, the largest military cataclysm until the wars with Nilfgaard. Falka, the rejected daughter of king Vridank of Redania, demands her rights and rebels against the nobility, gaining the support of the peasantry. The bloody madness spills out to all lands north of the Yaruga. The rebellion is quelled at the cost of horrible atrocities. Falka herself is burned at the stake.
1166
The adventurer Korin and the sorceress Visenna meet at the fork of the Ina and the Yaruga. Together they defeat the Koschchey that was prowling the Klamat pass (short story The Road of No Return).
1167
Probable birth date of Geralt, the future White Wolf.
1221
Witcher Geralt of Rivia, son of the sorceress Visenna, bloodily disposes of the band led by Renfri, who wanted to terrorize the Arc Coast town of Blaviken. He thus earns the soubriquet "Butcher of Blaviken" (short story The Lesser Evil).
1235
Geralt lifts the curse off Nivellen, who was turned into a beast (short story A Grain of Truth).
1239
Nilfgaard sparks the Northern Wars, invading lands south of the Amell Mountains.
1244
Geralt and Dandelion first meet at a festival in Gulet, then set out to the Valley of Flowers, where they nearly die at the hands of elven guerrillas (short story Ath the Edge of the World). In Rinde, Redania, Geralt meets the sorceress Yennerer and falls in love with her (short story (The Last Wish).
1245
An upheaval in Poviss, king Rhyd is overthrown and the crown returns to the rightful hands of the Thyssenid dynasty. Geralt is in Novigrad at the time (short story Eternal Fire).
1248
King Niedamir unsuccessfully tries to use a dragon hunt in the Kestrel Mountains to seize power over the duchy of Malleore. He is accompanied by Geralt, who, after four years of separation, meets Yennefer once again (short story Limits of the Possible)
In Brebervoord, the White Wolf is hired by prince Agloval to negotiate a bethrothal to the mermaid Sh'eenaz (short story A Little Sacrifice)
In Cintra, Geralt leads to the marriage of Pavetta and the Hedgehog of Erlenwald (short story A Question of Price).
1249
Geralt arrives in Vizima, where he lifts the curse off Princess Adda who was turned into a striga (short story The Witcher). Wounded by the striga, The White Wolf is healed at the Melitele convent in Ellander (short story The Voice of Reason).
Ca. 1250
Geralt and Yennefer stop at the town of Aedd Gynvael and part ways once again (short story A Shard of Ice).
1260
Delegated to Brokilon, Geralt meets the Cintrean princess, Ciri, bound to him by the Law of Surprise (The Sword of Destiny).
1261
The First Nilfgaardian War. The conflict breaks out in the summer, and the whole of Cintra falls into the hands of the invaders - queen Calanthe dies, princess Ciri disappears without a trace. The aggressors are thwarted only in the autumn months, following the second battle of Sodden. The first Nilfgaard-allied non-human guerrilla units appear - the Scoia'tael (Squirrels).
1262
In Malleore, Geralt takes a contract for a Leshy (comic book Reasons of State). In the autumn, Geralt returns south. Near Sodden, he rescues the merchant Yurga, getting wounded in the process. In the merchant's home, he meets Ciri again (short story Something More). He takes her to Kaer Morhen as his adopted daughter, to train her as a witcher (begginning of The Witcher Cycle)
1263
Geralt sends Ciri off to Ellander, where Yennefer begins training the girl to become a sorceress (vol. I of the Cycle)
1264-1265
The Second Nilfgaardian War, also called the Great War. Sparked by a sudden attack by the Empire on lands north of the Yaruga. It coincides with a mage rebellion on the isle of Thanedd, where sorcerers supporting Nilfgaard battle opposing mages. The flame of war engulfs most of the lands north of the Yaruga. Aedirn, Lyria and Rivia among others fall prey to the invaders. The war culminates with Nilfgaard's defeat in the battle of Brenna in the spring of 1265, followed by the Cintrean Peace Treaty. One again, the Empire retreats beyond the Yaruga, keeping Cintra (vol. 2-5 of The Witcher Cycle).
The disappearance of Ciri (on Thanedd) and Geralt's journey south in hopes of finding her (vol. 2-5 of the Witcher Cycle). The Witcher reunites with his adopted daughter, but on their way back, half way through 1265, he is severely wounded during the riots in Rivia and disappears without a trace.
1266 (or 1268 according to Effenberg & Talbot's Encyclopaedia Maxima Mundi published after 1350)
The first and worst outbreak of the blood fever epidemic known as the Red Death or the Catriona Plague.
1268 according to Effenberg & Talbot's Encyclopaedia Maxima Mundi published after 1350.
The official end of the Northern Wars fought by Nilfgaard (presumably, the Empire continued fighting beyond the Cintrean Peace in lands south of the Amell Mountains).
1270
Struck by amnesia, a wounded Geralt arrives at Kaer Morhen (beginning of The Witcher game).
***
***
In his novels and short stories, Andrzej Sapkowski often didn't pay much attention to the exact chronology of events, so the dates below are often only approximations. However, they do offer a cursory look at the history of the witcherverse. They were mostly established according to the seven books, the pen & paper role-playing game Wiedźmin - Gra Wyobraźni (The Witcher - A Game of Imagination) along with its expansions and materials available at www.sapkowki.pl
Distant past
The lands that will one day be roamed by Geralt of Rivia are first settled by gnomes and dwarves.
Later, 1000 years before humans, elves arrive on white ships and wage wars against the dwarves.
Ca. 746
The humans arrive - their First Landing takes place at the mouth of the Yaruga river and the Pontar delta. They begin the brutal conquest of the newly discovered lands, driving away the elves.
1062-1063
The elves, driven away to the east and unaccepting of coexistence with humans; take up arms under the lead of Aelirenn, also known as the White Rose. The insurgents suffer defeat, and there is a massacre of elven youth.
1161-1163
Falka's Rebellion, the largest military cataclysm until the wars with Nilfgaard. Falka, the rejected daughter of king Vridank of Redania, demands her rights and rebels against the nobility, gaining the support of the peasantry. The bloody madness spills out to all lands north of the Yaruga. The rebellion is quelled at the cost of horrible atrocities. Falka herself is burned at the stake.
1166
The adventurer Korin and the sorceress Visenna meet at the fork of the Ina and the Yaruga. Together they defeat the Koschchey that was prowling the Klamat pass (short story The Road of No Return).
1167
Probable birth date of Geralt, the future White Wolf.
1221
Witcher Geralt of Rivia, son of the sorceress Visenna, bloodily disposes of the band led by Renfri, who wanted to terrorize the Arc Coast town of Blaviken. He thus earns the soubriquet "Butcher of Blaviken" (short story The Lesser Evil).
1235
Geralt lifts the curse off Nivellen, who was turned into a beast (short story A Grain of Truth).
1239
Nilfgaard sparks the Northern Wars, invading lands south of the Amell Mountains.
1244
Geralt and Dandelion first meet at a festival in Gulet, then set out to the Valley of Flowers, where they nearly die at the hands of elven guerrillas (short story Ath the Edge of the World). In Rinde, Redania, Geralt meets the sorceress Yennerer and falls in love with her (short story (The Last Wish).
1245
An upheaval in Poviss, king Rhyd is overthrown and the crown returns to the rightful hands of the Thyssenid dynasty. Geralt is in Novigrad at the time (short story Eternal Fire).
1248
King Niedamir unsuccessfully tries to use a dragon hunt in the Kestrel Mountains to seize power over the duchy of Malleore. He is accompanied by Geralt, who, after four years of separation, meets Yennefer once again (short story Limits of the Possible)
In Brebervoord, the White Wolf is hired by prince Agloval to negotiate a bethrothal to the mermaid Sh'eenaz (short story A Little Sacrifice)
In Cintra, Geralt leads to the marriage of Pavetta and the Hedgehog of Erlenwald (short story A Question of Price).
1249
Geralt arrives in Vizima, where he lifts the curse off Princess Adda who was turned into a striga (short story The Witcher). Wounded by the striga, The White Wolf is healed at the Melitele convent in Ellander (short story The Voice of Reason).
Ca. 1250
Geralt and Yennefer stop at the town of Aedd Gynvael and part ways once again (short story A Shard of Ice).
1260
Delegated to Brokilon, Geralt meets the Cintrean princess, Ciri, bound to him by the Law of Surprise (The Sword of Destiny).
1261
The First Nilfgaardian War. The conflict breaks out in the summer, and the whole of Cintra falls into the hands of the invaders - queen Calanthe dies, princess Ciri disappears without a trace. The aggressors are thwarted only in the autumn months, following the second battle of Sodden. The first Nilfgaard-allied non-human guerrilla units appear - the Scoia'tael (Squirrels).
1262
In Malleore, Geralt takes a contract for a Leshy (comic book Reasons of State). In the autumn, Geralt returns south. Near Sodden, he rescues the merchant Yurga, getting wounded in the process. In the merchant's home, he meets Ciri again (short story Something More). He takes her to Kaer Morhen as his adopted daughter, to train her as a witcher (begginning of The Witcher Cycle)
1263
Geralt sends Ciri off to Ellander, where Yennefer begins training the girl to become a sorceress (vol. I of the Cycle)
1264-1265
The Second Nilfgaardian War, also called the Great War. Sparked by a sudden attack by the Empire on lands north of the Yaruga. It coincides with a mage rebellion on the isle of Thanedd, where sorcerers supporting Nilfgaard battle opposing mages. The flame of war engulfs most of the lands north of the Yaruga. Aedirn, Lyria and Rivia among others fall prey to the invaders. The war culminates with Nilfgaard's defeat in the battle of Brenna in the spring of 1265, followed by the Cintrean Peace Treaty. One again, the Empire retreats beyond the Yaruga, keeping Cintra (vol. 2-5 of The Witcher Cycle).
The disappearance of Ciri (on Thanedd) and Geralt's journey south in hopes of finding her (vol. 2-5 of the Witcher Cycle). The Witcher reunites with his adopted daughter, but on their way back, half way through 1265, he is severely wounded during the riots in Rivia and disappears without a trace.
1266 (or 1268 according to Effenberg & Talbot's Encyclopaedia Maxima Mundi published after 1350)
The first and worst outbreak of the blood fever epidemic known as the Red Death or the Catriona Plague.
1268 according to Effenberg & Talbot's Encyclopaedia Maxima Mundi published after 1350.
The official end of the Northern Wars fought by Nilfgaard (presumably, the Empire continued fighting beyond the Cintrean Peace in lands south of the Amell Mountains).
1270
Struck by amnesia, a wounded Geralt arrives at Kaer Morhen (beginning of The Witcher game).
***