Date of writing
According to Judges 18:30, ‘Jonathan, descendant of Gershom, son of Moses, and his descendants served as priests for the tribe of Dan until the time of the exile.’
This indicates that the book of Judges (at least, in its final form) was not written until some 500 years after the events it describes.
Block agrees that this is probably ‘a reference to the deportation of the population of Dan by Tiglath Pileser III to Assyria in 734 B.C. (2 Kgs 15:29).’