According to Persian mythology, the ancient king credited with establishing Nowruz is Jamshid.
The story appears most famously in Ferdowsi’s Shahnameh, the Persian national epic. In the legend, Jamshid saves humanity from a deadly winter by constructing a jewel-studded throne. Demons lift him above the earth, where he shines like the Sun. His subjects gather in wonder, scatter jewels around him, and proclaim the occasion a “new day”—Nowruz.
This is a mythological attribution, not a securely documented historical claim. Nowruz has roots in ancient Iranian religious and seasonal traditions, and its precise origin is debated. The festival is associated with the spring equinox and the renewal of life; later calendar reforms fixed the Iranian New Year to the equinox.
Jamshid is sometimes confused with historical Persian rulers such as Cyrus, Darius, or Alexander. Those kings are connected with documented empires, whereas Jamshid belongs to Iran’s legendary royal tradition and is linked to Nowruz through epic literature.