In the beginning of the Treta Yuga, Vivasvat gave the knowledge of this religion to Manu. Manu, for the protection and support of all the worlds, then gave it to his son Ikshvaku.
त्रेतायुगादौ च ततो विवस्वान् मनवे ददौ। मनुश्च लोकभूत्यर्थं सुतायेक्ष्वाकवे ददौ॥