Whatever Brahmâ told Atharvan, that knowledge of Brahman Atharvan formerly told to Angir; he told it to Satyavâha Bhâradvâga, and Bhâradvâga told it in succession to Angiras.

In plain words: Atharvan passed this knowledge to Angir. Angir taught it to Satyavaha Bharadvaja, who then passed it on to Angiras. It was handed down from teacher to student.