Every city was governed by elders (see Deuteronomy 19:12; Judges 8:14). For the number “ten,” compare Exodus 18:25. Probably the presence of, at least, ten elders was necessary to make a lawful public assembly, as among modern Jews ten (a minyon) are necessary to constitute a synagogue.
Related Commentaries of Ruth 4:2
Ruth 4:2
2 And he took ten men of the elders of the city, and said, Sit ye down here. And they sat down.