There were several conflicts with the Akaviri. The most recent at the time of ESO's setting would have taken place ten years prior. According to lore, it was a short-lived skirmish.

However it has been mentioned in several lorebooks.

From Jorunn the Skald King (appears in ESO only)

Jorunn was in Riften when the Akaviri of Dir-Kamal assaulted the northeast coast of Skyrim in 2E 572. Jorunn and his closest comrades, the “Pack of Bards,” fought their way up the coast to Windhelm, arriving just in time to see its gates breached by the Akaviri. Jorunn hurled himself into the fray, street-fighting being something he had experience with, but was unable to prevent the fall of the city and the slaying of Queen Mabjaarn and the Princess Nurnhilde, who both went down fighting.

That book goes on to detail more of the fighting.

From Varieties of Faith (appearing in Morrowind and Skyrim: Dragonborn)

Vivec (Master of Morrowind): Warrior-poet god of the Dunmer. Vivec is the invisible keeper of the holy land, ever vigilant against the dark gods of the Volcano. He/she has saved the Dunmeri people from certain death on numerous occasions, most notably when he/she taught them how to breathe water for a day so that he/she could flood Morrowind and kill the Akaviri invaders, ca. 2E572.

So yeah ZOS probably grabbed the tidbit mentioned in an earlier book and expanded upon it to dramatic effect. But yes the war had been mentioned albeit briefly prior to ESO.

More info if you're curious:

Lore:Akavir - general overview of the history

Second Era 2E 572 - direct link to a small blurb about the conflict.