I'm not sure about new lore but old lore would also imply that this is around when the Institute of War would be founded to stop such rampant outbreak of war across the entirety of Runeterra via exhibition matches between different factions and countries to settle disputes. Factions and countries popping up near everywhere and waging war until greater countries eventually formed and expanded as Noxus, Demacia, etc. I think that's enough to get a semblance of something, most likely during the Rune Wars maybe, since according to league lore that that was the most fractured the world had been. Alongside that we have all the lore given from Legends of Runeterra, the in-game lore from the characters themselves, the lore they've given on their forums, all of their animatics, and even with the advent of their new show coming Arcane. Click to expand.Really? They have an entire world map full of history on it.