Who is traditionally credited with composing the Gathas?

The Gathas—the oldest part of the Avesta—are traditionally credited to Zoroaster (also known as Zarathustra), the founder of the Zoroastrian religion.12

These hymns are written in a specific, archaic dialect often referred to as Gathic, which differs from the language found in the rest of the Avestan texts. While the exact historical period of Zoroaster remains uncertain, he is traditionally ascribed to the 7th to 6th century BCE.231