Ezra 2:21

the men of...the descendants of: Some returnees were identified by their hometowns. Not everyone knew their family history or had famous ancestors. Most cities mentioned were near Jerusalem.

This chapter is Ezra's first major digression from the main story. The returning exiles needed to identify true Jews to maintain their community identity and theological purity. This helped them know whom they could marry and who could worship at the temple. This list is not the initial list of all Jews who returned to Jerusalem (compare Nehemiah 7:6–73). Instead, it is a slightly later list, created after Sheshbazzar died, of people who had settled in their towns.