E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
A title of honour, common with the old poets, as Dan Phbus, Dan Cupid, Dan Neptune, Dan Chaucer, etc. (Spanish, don.)
Dan Chaucer, well of English undefiled,
On Fames eternal beadroll worthy to be filed.
Spenser: Faërie Queene, book iv. canto ii. 32.
From Dan to Beersheba. From one end of the kingdom to the other; all over the world; everywhere. The phrase is Scriptural, Dan being the most northern and Beersheba the most southern city of the Holy Land. We have a similar expression, From John o Groats to the Lands End.