1400BC is the approximate biblical date for the Conquest of the Promised Land by the Israelites.
In fact, a 1400BC date seems so certain, based on solid evidence, that we cannot help but wonder whether many scholars have simply ignored Garstang and gone with Kenyon for their own personal reasons.
On the other hand, if the date of the Conquest is again acknowledged to be about 1400BC, then these bands of intruders could well be considered as describing hostilities early in the period of the Judges.