There was already a Jewish community established in the region of Rome, Italy when the Judaean Maccabean rebels sent a well received emissary there in 161 BCE. Under Roman rule, they were as oppressed or free as their Jerusalem coreligionists. In 212 CE, Emperor Caracalla made all imperial subjects citizens, with the rights to property ownership and the duty of taxes. This citizenship extended to the Jewish population, and there was a century of prosperity.
Constantine, the first Christian Emperor who moved the capitol to Byzantium, conquered Italy in 312. In 315, he accused all Jews of being “Christ-killers”. His son Constsantius carried on the family tradition of Jew hate. He labeled Judaism “a pernicious sect” in 337. Emperor Theodosius II barred Jews in 404 CE from certain government jobs. Over the next 123 years successive rulers added more restrictions, which Jews continued to defy as they could. Bans on new synagogue construction were flouted for at least three centuries in a row, according to archaeological records.
Justinian ruled that Jews could not publicly read the Mishnah, so they composed poetry which referred to it instead, called piyutim. These poems became important works in their own right and the acts of resistance were unifying. One of the other rules they’d flouted was buying Christian slaves. Christians owning Jewish slaves was perfectly legal agricultural practice, but the reverse was considered a nefarious plot to convert good Christians away from the faith. Inherited slaves were grudgingly permitted, but purchasing new ones was not.
In 517 CE, the Civil Code of Emperor Justinian was designed to crack down on the illegal slave trade. He stopped the practice of compensating for lost slaves in cases of illegal purchase and in its place instituted a thirty pound gold fine. Any Jew found in the possession of an illegally purchased Christian slave could be put to death. The laws were extreme, but unevenly enforced. In most of Italy Jews held a higher status than other non-Christian minorities; a Jew might be called on to testify against a Christian on behalf of the state in court.
The Jews of Italy were still always second class, which may explain why they supported Persian Sassanid (602-628) and Arab Muslim invaders against their Roman Byzantine masters. The empire they were citizens of was not overthrown quite then either time, but the Jewish lack of loyalty did lead to some brief retaliation. Then about half of Italy fell under Lombard (Germanic) rule in 565, with the occasional Frankish invasion before and after. Byzantine Rome was too preoccupied to worry itself with persecution of second class citizens, and Jews enjoyed nearly two centuries of only regular worries like plague and famine (both contemporary events in Italy then.)