Ezra 4 begins with a narrative, telling us about what happened in Jerusalem, and goes on to mention several letters that were sent to the king of Persia. A large part of Ezra 4 is also written in Aramaic (Ezra 4:8–24) and not in Hebrew.
Ezra 4 contains a long parenthetical remark, a comment inserted as an explanation or afterthought into a passage that is grammatically complete without it. (E.g., Peter (who is forty-five years old) went to the shop.
The sentence will still make sense without the information in parentheses.) The information from Ezra 4:6 to Ezra 4:23 can be considered as a parenthetical statement.1 The Bible writers did not use actual parentheses like we do today. Instead, they signalled a parenthetical comment by repeating information. If you look carefully at Ezra 4:5 and Ezra 4:24, they both mention the reign of Darius king of Persia. This helps us to know that the rest of the information is not about the opposition that took place when the temple was rebuilt, but an example of similar opposition that took place at a later date.
If we recognize this parenthesis, we can divide Ezra 4 as follows:
Opposition to rebuilding the Temple (Ezra 4:1–5)
An offer of help (Ezra 4:1–2)
A refusal (Ezra 4:3)
Opposition to the Jews building the Temple (Ezra 4:4–5)
[Opposition to rebuilding the walls (Ezra 4:6–23)
A letter written to king Xerxes (Ezra 4:6)
A letter written to king Artaxerxes (Ezra 4:7–16)
A letter written by king Artaxerxes to Rehum (Ezra 4:17–22)
Opposition to the Jews building the walls (Ezra 4:23)]
Conclusion (Ezra 4:24)
The work of building the Temple came to a stop (Ezra 4:24)
1 Now when the adversaries of Judah and Benjamin heard that the returned exiles were building a temple to the LORD, the God of Israel,