At the end of Ezra 6, it was a time of joyful celebration. We see the first wave of exiles celebrating with joy all that God had done through them.
More than 50 years elapsed between the end of chapter 6 and the beginning of Ezra 7. During this timeframe, the events in Esther take place. The events in the book of Esther occurred from 483 BC to 473 BC, during the first half of the reign of King Xerxes, who chose Esther as his Queen. During this time, the first remnant of Jews who had returned to Judah struggled to reestablish temple worship according to the Law of Moses. But Esther and Mordecai, along with many other Jews, had chosen not to make the trek back to Judah. They seemed content to stay in Susa, the capital city of Persia, in which the story is set (Source: insight.org). The sovereignty and faithfulness of God permeated each scene in the book of Esther; this pattern continues in the book of Ezra.