Having been born from the womb of Rathītara’s wife, all these sons were known as the dynasty of Rathītara, but because they were born from the semen of Aṅgirā, they were also known as the dynasty of Aṅgirā. Among all the progeny of Rathītara, these sons were the most prominent because, owing to their birth, they were considered brāhmaṇas.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
एते क्षेत्रे प्रसूता वै पुनस्त्वाङ्गिरसाः स्मृताः । रथीतराणां प्रवराः क्षत्रोपेता द्विजातयः
ete kṣetre prasūtā vai punastvāṅgirasāḥ smṛtāḥ | rathītarāṇāṃ pravarāḥ kṣatropetā dvijātayaḥ
SB 9.6.3