Final answer:
The Pharisees were a significant religious and political group among the Jewish population of Judea during the first century CE, advocating that all Jews should follow the laws of Moses and heralding the arrival of a messiah.
Step-by-step explanation:
The group among the Jewish population of Judea were the Pharisees. During the first century CE, Jewish society faced internal divisions with various sects vying for influence. The Pharisees were a significant religious and political faction who insisted that all Jews should follow the complete body of laws given by Moses, and also preached the coming of a messiah. They opposed the Sadducees, who were another powerful priestly group with differing religious interpretations. On the other hand, groups like the Essenes and the Zealots also contributed to the complex tapestry of Judean society.