It is not myth. It is written on stones.
1. The word 'Ezhava' appears in the 'Arithapetti' stone inscriptions of third century BCE - period of Emperor Asoka ( BCE 273-232).
2. A cave-inscription at 'Kilavalavu' near Cannanore also mentions about Ezhavas.
3. Again 'Ezhavan' in Alakaarmalai inscription of second century BCE.
4. In 'sithannavaasal' cave- inscription of same period.
5. In Thiruppuramkuntam cave, first century BCE.
6. 'Ezhavan' in cave inscription of the same period at Siddhaarmalai.
The above inscriptions mention about donations made by Ezhavas to Buddhist Viharas and Jain temples. ( Only kings and rich merchants used to make such donations).
Research Scholars presented reports in All India Oriental Conference held at Pune in 1919. The observation was accepted by the conference.
There were rich Ezhavas in South India 2250 years ago.