[4] The current view is that the area is named after Agmundr, a Norse warlord, vassal of Eowils, Halfdan and Ingwaer, co-kings of Jorvik, all four of whom died at the Battle of Tettenhall near Wednesfield and Wolverhampton in August 910;[5] Partington's early 20th-century description of "Amounder ... the first Viking who settled in the Fylde country" now being considered more fanciful than historically accurate.

[4] In fact, the grant itself has not survived, its only source being an early 8th-century hagiography of the Northumbrian bishop Wilfrid – Vita Sancti Wilfrithi – by Stephen of Ripon (also known was Eddius Stephanus).

The historical misattribution may be due to the 16th-century antiquarian John Leland who cites Hasmundesham (possibly Amounderness) in his Collectanea, originally published in 1632, but does so without proper supporting evidence.

However, Thorn argues that "it was only along the river Hodder on the western and south-western edges of the Forest of Bowland that the division between Amounderness and Craven corresponded in any way to the later boundary between Lancashire and Yorkshire".

Indeed, he even suggests that Amounderness may have been a "subdivision of Craven" which he describes as "stretching from the Irish Sea over the Pennines to touch the Yorkshire wapentakes of Burghshire and 'Skyrack'" ... the area around the headwaters of the rivers Aire and Wharfe and upper Ribblesdale".

It included Bispham, Blackpool, Broughton-in-Amounderness, Chipping, Cockerham, Garstang, Kirkham, Knott End-on-Sea, Mitton, Pilling, Preesall, Poulton-le-Fylde, Preston, and Ribchester.

In his 1858 novel Mervyn Clitheroe, William Harrison Ainsworth portrays the minor character of the Earl of Amounderness whose "sylvan domains ... at Dunton Park ... boasted much noble timber".

It comprised the civil parishes of Barton, Broughton, Cuerdale, Farington, Fulwood, Goosnargh, Grimsargh, Haighton, Hutton, Lea, Little Hoole, Longton, Much Hoole, Penwortham, Samlesbury, Walton-le-Dale, Whittingham and Woodplumpton (all of which were transferred to Preston and South Ribble registration district in 1974), and Alston, Dilworth, Dutton, Hothersall and Ribchester (which were transferred to Ribble Valley registration district).