The Essenes were the devoted to righteousness, they did everything in agreement with each other. They also believed that the others sects had corrupted the city and Temple. Which then the Essenes moved out of Jerusalem and into the desert where they lived monastically. What makes them the intriguing sect, is that they would go into the mountains with scripts and teachings, the most valued of the Old Testaments that are used today were found. The Dead Sea Scrolls are also assumed to be edited by the Essenes. They considered themselves to be separate people because of the knowledge they held within.
The spread of the religion was forced because the Jews were diligent with their religion. They had a devotion to one God that was not scene by the Romans. If at any time the Jews were exiled their religion would follow them. "The Romans referred to the Jews as porcupines. Just as a porcupine is an animal that even great predators avoid, so too the Jews. Even if you ate it you would be sorry." Although the Jews were not military practitioners nor politicians, it was their religion morality that separate them. When Pompey the Great came to Jerusalem he was utterly respective of the place. Caesar advocate to Jews is assassinated, it's shortly after in 44 B.C., when Rome is now among Judaism under Augustus. At the same time Judea was being taken into Roman province.
The highest exalt of Judaism was would be under Augustus. There were even two synagogues that were built in Rome by Jewish slaves under the Claudian. At this time period 27 B.C. to 14 C.E. the Jews were at ease in Rome free to practice their religion and become citizens of Rome, in fact they were. Judea was still under Roman rule and August appointed Herod the Great as King of Judea, while he continued the expansion of Rome. The Zealots the fourth sect of Judaism would be founded under the Augustus.
The Zealots were very radical and vehement, they have the most uproaring spirit of denying oppression and defying Roman rule. (By 66 A.D., They had a large component of Jews and they go to the extreme against the Roman oppressors, initiating a long courageous war but that finally ended with the inevitable Roman victory and the desolation of the Second Temple). By A.D. 70 Jerusalem would fall.