As with western Scotland, most of our knowledge comes from research-based archaeology since there has been relatively little developer-funded archaeology in this region. Key contributions have been made by Audrey Henshall's study of the region's megalithic monuments (Henshall 1972); by Lindsay Scott's excavations (including at Eilean an Tighe, North Uist (Scott 1951); by Ian Armit's excavation at Eilean Domhnuill, Loch Olabhat, North Uist (e.g. Armit 2003); by Patrick Ashmore's excavations at Calanais in 1980 and 1981 (Ashmore forthcoming), along with Clive Ruggles' assessment of its archaeo-astronomical aspects and by the Pontings'/Curtis' research in the area; by Derek Simpson's excavations at Northton, Harris (Simpson et al. 2006); and by the campaigns of the Universities of Sheffield and Cardiff on Benbecula and South Uist (Branigan & Foster 2000; Parker Pearson et al. 2004; Parker Pearson 2012).
It appears that this region was first colonised by farming communities as part of a secondary expansion of 'the Neolithic': at any rate, there is no evidence for the early CB Neolithic, and no firm evidence for the Atlantic façade, Breton Neolithic has yet been found - although examination of the simplest passage tombs in the region would be worthwhile. There are, however, elements of both of these Neolithic traditions, with passage tombs representing a development from the earliest form as seen at Achnacreebeag, and with North Uist megaliths - especially Clettraval - showing elements of both the passage tomb and the Clyde cairn traditions (Henshall 1972; Henley 2004). The date of 'the Neolithic's' appearance is likely to be during the late 38th century.
Radiocarbon dating of developments over the 4th millennium is particularly poor in this region, and so, although it is known that stone (and probably turf)-built houses were constructed - at Eilean Domhnuill - details of the chronology of settlement and chamber tomb construction (and use of Hebridean Neolithic pottery) leave a lot to be desired. Furthermore, next to nothing is known about settlement on the north-west mainland of Scotland, even though the megalithic tombs form part of Henshall's 'Orkney-Cromarty-Hebrides' grouping.
Armit's excavations at Loch Olabhat provided a fascinating insight into the pressures on land use during the Neolithic, although his model of a squeeze between rising sea levels and expanding blanket peat (Armit 2003) has not been universally accepted (see Theme 4).
That communities in this region maintained contacts to the south and the north is demonstrated in finds such as an Antrim porcellanite axehead in a haft at Shulishader, Lewis, and of finds of pitchstone - showing links to the south- and in the sharing of Unstan Bowls, which demonstrates contacts with Orkney and/or the north-east mainland.
As in western Scotland, an understanding of what happened between 3500 and 3000 BC is not as clear as would be liked, even though some of the Hebridean Neolithic pottery will certainly have been in use, as was the settlement at Eilean Domhnuill.
Late Neolithic developments are dominated by the construction of Calanais, in the first instance as a stone circle with a central monolith (Ashmore forthcoming), probably around 3000/2900 BC. This act - associated with a single Grooved Ware pot of a style closely comparable with Orcadian Grooved Ware - formed part of the southward spread of traditions and practices from Orkney. The lunar orientation of Calanais may have been planned from the outset, but was emphasised by the subsequent addition of avenues along the cardinal points.
Key research questions are:
- The near-absence of evidence for Early Neolithic settlement on the north-west mainland needs to be redressed
- The dating of the appearance of 'the Neolithic' in this region needs to be clarified, as does the dating of subsequent developments
- To what date belong the plethora of small stone circles around the main ceremonial site at Calanais?