Bhagavatapurana 12.6.78

12.6.78

udīcyāḥ sāma-gāḥ śiṣyā āsan pañca-śatāni vai /
pauṣyañjy-āvantyayoś cāpi tāṃś ca prācyān pracakṣate //

78. The northern disciples versed in Sama Veda were indeed five hundred, who learnt as many branches as they were in number; there were also disciples of Paushyanji, Avantya and Hiranyabha; some call these eastern disciples.