After 600, information on the Britons of Alt Clut becomes slightly more common in the sources. However, historians have disagreed as to how these should be interpreted. Broadly speaking, they have tended to produce theories which place their subject at the centre of the history of north Britain in the Early Historic period. The result is a series of narratives which cannot be reconciled. More recent historiography may have gone some way to addressing this problem. At the beginning of the 7th century, Áedán mac Gabráin may have been the most powerful king in northern Britain, and Dál Riata was at its height. Áedán's byname in later Welsh poetry, Aeddan Fradawg (Áedán the Treacherous) does not speak to a favourable reputation among the Britons of Alt Clut, and it may be that he seized control of Alt Clut. Áedán's dominance came to an end around 604, when his army, including Irish kings and Bernician exiles, was defeated by Æthelfrith at the battle of Degsastan. It is supposed, on rather weak evidence, that Æthelfrith, his successor Edwin and Bernician and Northumbrian kings after them expanded into southern Scotland. Such evidence as there is, such as the conquest of Elmet, the wars in north Wales and with Mercia, would argue for a more southerly focus of Northumbrian activity in the first half of the 7th century. The report in the Annals of Ulster for 638, "the battle of Glenn Muiresan and the besieging of Eten" (Eidyn, later Edinburgh), has been taken to represent the capture of Eidyn by the Northumbrian king Oswald, son of Æthelfrith, but the Annals mention neither capture, nor Northumbrians, so this is rather a tenuous identification. In 642, the Annals of Ulster report that the Britons of Alt Clut led by Eugein son of Beli defeated the men of Dál Riata and killed Domnall Brecc, grandson of Áedán, at Strathcarron, and this victory is also recorded in an addition to "Y Gododdin". The site of this battle lies in the area known in later Welsh sources as Bannawg--the name Bannockburn is presumed to be related--which is thought to have meant the very extensive marshes and bogs between Loch Lomond and the river Forth, and the hills and lochs to the north, which separated the lands of the Britons from those of Dál Riata and the Picts, and this land was not worth fighting over.