Hadrian and the Fall of Syria
In 870*, Hadrian became emperor of Rome. Unlike his predecessor, he valued stability more than expansion. He returned Assyria to the Persians soon after his ascension, although he did decide to keep Armenia and Mesopotamia, although he did create a massive Romanization of the two new provinces. This process was made possible by the not insignificant Jewish presence in the area. Jews had been regarded for the last few decades as loyal to the Empire. Even outside the Empire, Jews looked to Rome as a land accepting of Jews. Unfortunately, this backfired in the years leading up to the Trajan's wars, since the Persians now looked at Jews with a deep sense of mistrust. By the time of the Susa massacre in 873, virtually all remaining Jews in Persia moved to Judaea.
Meanwhile, Hadrian was becoming well known as an emperor of peace. He successfully made peace with the Persians a few years into his reign. He built formidable defenses throughout his borders, the most famous of which is his wall in Britannia, later known as Hadrian's Wall. He patronized the arts and had a virtual obsession with Greek culture. He was also well known for his travels all over the Empire. Among his travels was to Judaea in 883, where he received a rousing welcome from the Jews. When he went to Jerusalem, the High Priest personally sacrificed a dozen beautiful cows in his name. For the Judaeans, life couldn't get better. The same could not be said for the remaining pagan Syrians.
In the Levant, paganism were a dying religion. Although Judaism never went out converting the pagans, the pagans, disgusted with their own religion and fascinated with Judaism, converted in droves. The remaining Syrian pagans began to loath Judaism. Although they were free to practice their religion, many hated how the Jews took most of their province. But what really infuriated them was how Rome would allow such a thing to happen. From Tyrus to Antioch, Syrians plotted a rebellion against the hated Romans and Jews. Two years after Hadrian's visit to Judaea, they initiated their rebellion. All over the Levant, the pagans rose up and massacred the Jews and Romans. They quickly proclaimed a new, independent Syria, with the capital in the great city of Antioch.
Hadrian, shocked that the Syrians would dare do such a thing, quickly sent his legions to squash the rebellion. But even with the help of the legions, the Romans might have lost if it weren't for the Jews and the general Simon bar Kosiba. Called bar Kochba by the Jews for his heroism, the Romans remember him as a formidable general in the fight against the Syrians. It became the stuff of legend when he saved an entire legion from defeat. By 888, the rebellion was crushed.
With the rebellion over, Hadrian sent Bar Kochba to Rome, where he gave the heroic general a Triumph, the first Jew to ever receive one. He also gave him Roman citizenship and a rich plot of land in old Syria. He also gave the Jews more rights than ever and virtually all of the Levant, stretching all the way to Antioch. This was made easier by the increasing disappearance of Syrian pagans. Following the rebellion, most pagans were horrified by what the war has brought down upon them. And after seeing the Jews morality in warfare, they converted to Judaism in increasingly large numbers.
This causes some controversy among the Jews. Some want to welcome them with open arms, while others want to severely restrict conversion. Eventually, Rabbi Akiva suggests a popular compromise. First, a convert follows some, but not all, of the laws in what is essentially an initiation stage. During this time, the initiate learns Judaism from a rabbi. After the rabbi decides the man is ready to be considered a Jew, he is circumcised and is considered a full Jew in all but one aspect; they are only allowed to marry someone born Jewish, in order to avoid the possibility of residual pagan feelings to manifest. Although some would-be converts don't like this initiate stage and still have bad feelings towards circumcision, most agree to this process. Within a decade of the rebellion's end, the Levant has become virtually entirely Jewish.
* - I decided to start using the Roman calendar to signify dates. If you want to know what year it actually is, just subtract the year shown by 753. For instance, 870-753=117.