Josephus lived in the 1st century and would accurately report the history in that time period. However he does report about the activities of the Patriarchs. These stories are found in the Jewish Bible, however not with many of the descriptions found in Josephus' work.
For example, Josephus says of Abraham in Antiquities of the Jews, Book I, chap. 8 sec. 2:
He communicated to them arithmetic, and delivered to them the science of astronomy; for before Abram came into Egypt they were unacquainted with those parts of learning; for that science came from the Chaldeans into Egypt, and from thence to the Greeks also.
How did he know this?