What does Judges 18:9 mean?

Dan, one of the tribes that was allotted land in Canaan (Numbers 3:5–10), is feeling cramped. This is because they failed to fully control their assigned territory (Judges 1:34–36). Rather than complete that conquest, they send advance scouts to look for other territory they can take. That leads the "spies" to an area called Laish, occupied by a peaceful group of Sidonians and rich in natural resources. These people are repeatedly referred to as "unsuspecting" (Judges 18:7, 10). This means they are unprepared for war and would be seen as an easy target.

Perhaps some of the Danites hearing this report objected to moving so far away. The location in question would have been several days' journey, even for scouts. It's not a nearby territory. Yet the five scouts are insistent. They say it's time for their tribe to get up, go, and attack. They know the land is good and beautiful. The scouts see no reason to hesitate. Now is the best time to act.

The scenario is a perverse echo of the days when the Israelites first came to the Promised Land. They too sent spies in to scout the territory. Those spies also returned with reports that the land was good. In that case, though, most of the scouts said Israel could never defeat the people of Canaan (Numbers 13:25—14:10). They were wrong, since God had given that land to His people and would bless their efforts to take it. Perhaps the memory of that story motivated these spies to be especially positive about the opportunity to possess a new land. And yet, the tribe of Dan is now enthusiastic about taking land they have not been given, which is not meant to be theirs, at all.