Please note that Mommsen uses the AUC chronology (Ab Urbe Condita), i.e. from the founding of the City of Rome. You can use this reference table to have the B.C. dates
His eighteen books
on the -Ius Civile-, which embraced the positive materials of
jurisprudence--legislative enactments, judicial precedents, and
authorities--partly from the older collections, partly from oral
tradition in as great completeness as possible, formed the starting-
point and the model of the detailed systems of Roman law; in like
manner his compendious treatise of "Definitions" (--oroi--) became
the basis of juristic summaries and particularly of the books
of Rules.
Although this development of law proceeded of course
in the main independently of Hellenism, yet an acquaintance with
the philosophico-practical scheme-making of the Greeks beyond
doubt gave a general impulse to the more systematic treatment of
jurisprudence, as in fact the Greek influence is in the case of
the last-mentioned treatise apparent in the very title. We have
already remarked that in several more external matters Roman
jurisprudence was influenced by the Stoa.(41)