Siganeul Dallineun Swordmaster

The Kingdom of Vanroah has fallen. Lansen, the last prince, flees with the remaining survivors to a faraway land. Vowing to one day revive the kingdom, he becomes a swordmaster at a young age, only for a treacherous incident to strip everything away. Powerless to protect those he loves, he uses an ancient artifact to travel 10,000 years back in time to the Age of the Arcane. There, its rich knowledge and wisdom help him avert disaster in the present. But each time he turns back the clock, new secrets emerge, entangling the past and present in ways he never foresaw.

(Source: WEBTOON)