Complex sentence: Being a court archivist allowed Sima to gather many sources (i.e. eighty texts in addition to memorials, edicts, and stone inscriptions) to enhance the enormous scope of his work, which mentions roughly four thousand people by name.
Split into simpler sentences: Being a court archivist allowed Sima to utilize eighty textual sources in addition to memorials, edicts, and stone inscriptions. These sources enhanced the enormous scope of his work, which mentions roughly four thousand people by name.