Thus I have described the royal dynasty of Manu, as it is known on this earth. One can similarly study the history of the vaiśyas, śūdras and brāhmaṇas living in the various ages.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
इत्येष मानवो वंशो यथा सङ्ख्यायते भुवि । तथा विट्शूद्रविप्राणां तास्ता ज्ञेया युगे युगे
ityeṣa mānavo vaṃśo yathā saṅkhyāyate bhuvi | tathā viṭśūdraviprāṇāṃ tāstā jñeyā yuge yuge
SB 12.2.35