Because all sacrifices were supposed to be limited to the temple in Jerusalem, during the exile the Jews could not perform their usual sacrifices nor observe any holidays, such as Passover, that would entail sacrifices. Instead, as we see in the book of Daniel, they focused on prayer in the direction of Jerusalem. Priests, such as Ezekiel, could preach and exhort, but they could not perform their regular duties. When King Cyrus sent the Jews back to Jerusalem, it was with the explicit instructions that they were supposed to rebuild the temple and restore the previous worship, which they did. Nevertheless, some things did change after the exile: 1) The Ark of the Covenant was irretrievably lost, and so the Holy of Holies was essentially empty; 2) There was no longer any temptation for the Jews to mix the worship of God with pagan idolatry, as there had been before; 3) When Antiochus Epiphanes, king of Syria, ruled the land, he defiled the temple by sacrificing a pig to Zeus on the altar; 4) His actions provoked the Maccabean revolt, resulting in the priests simultaneously acting as kings during the Hasmonean era, which was ended by the Romans; 5) Sometime in the course of things, the party of the Sadducees took ownership of the priesthood, so that by the first century C.E. you didn’t have to be a Sadducee to be a priest, and you didn’t have to be a priest to be a Sadducee, but usually the two overlapped almost entirely. The time without a temple during the Babylonian exile undoubtedly set some patterns for Jewish worship in synagogues after the temple was destroyed a second time in 70 C.E.