You've read this story before, but notice as you read this time that Ezra (the writer) ignores the Northern Kingdom of Israel after the split between Rehoboam and Jeroboam. Remember that Ezra is writing to the Jews returning from exile from Babylon. He is using the Temple as a unifying tool. The Temple is located in Jerusalem. It was the crown Jewel of unified Israel and proof of God's presence among them. He writes of Judah because that is where Jerusalem and the ruined temple are. As he calls Israel back to their roots and service to Yahweh, the temple is his unifying instrument.
Another note relative to Rehoboam and Jeroboam; what would have happened if Rehoboam had listened to the elders? I realize that youth has energy and idealism galore, but listening to our elders gives us experience and tradition. Some experiences are bad and some traditions should be changed and we should not do something just because that is what we have always done before. Nevertheless, some of the wisdom of our elders; sprinkled with the enthusiasm and idealism of youth would make a powerful force. Israel might have avoided a lot of misery had Rehoboam honored the wisemen who had served his father Solomon and the God that his grandfather David had loved so greatly.
As we seek to build up the Kingdom of God in the places where we live, work and serve; we should remember that each of us is gifted in different ways. Combining the gifts is the secret to a healthy church. This requires that each of us come with a spirit of unity to our labors. We listen to all voices and then seek God's inspiration (another error made by Rehoboam that led to the division of Israel). The result will be that God gives us victory as we walk together in pursuit of His more excellent way.
God bless you this week in your work and in your play that you will be a Godly example to those who look to you for an example of Christianity.