The Ulfberht Swords: Viking Age Supersteel

About 170 surviving blades carry the curious inscription +VLFBERH+T, forged between roughly 800 and 1000 AD. Ulfberht swords used crucible steel with a purity medieval Europe could not match for centuries, arriving through Viking trade routes that reached deep into Asia. Most European smiths of the day worked bloomery iron full of slag, so an Ulfberht cut cleaner and bent less, and fakes with misspelled inscriptions appeared almost immediately.

Researchers still debate who Ulfberht actually was: a master smith, a workshop, or an early brand name..