Adam Clarke on Judges 18:1

There was no king in Israel - See Jdg 17:6 (note). The circumstances related here show that this must have happened about the time of the preceding transactions.

The tribe of the Danites - That is, a part of this tribe; some families of it.

All their inheritance - That is, they had not got an extent of country sufficient for them. Some families were still unprovided for, or had not sufficient territory; for we find from Jos 19:40, etc., that, although the tribe of Dan did receive their inheritance with the rest of the tribes of Israel, yet their coasts went out too little for them, and they went and fought against Leshem, (called here Laish), and took it, etc. This circumstance is marked here more particularly than in the book of Joshua. See on Jos 19:47 (note).