At www.pasthorizonspr.com/index.php/archives/01/2014/manning-the-ramparts-a… … Sherriffields, a large crop mark 20 miles east of Edinburgh, turned out to be a ditch measuring 8m across and 2 to 3m deep, representing the enclosure ditch surrounding a major hill fort. It prduced a C14 date of AD211-384, right smack in the middle of Pictish expansion into southern Scotland and elsewhere. The 3rd century AD was a period of turmoil right across the Roman empire, or a spell of 20 years or so. Saxon pirates sailed the English Channel unchallenged and everywhere on it's frontiers, from Britain to the Near East, the Romans were under pressure from restless tribes on the move. What set the Picts in motion is unknown, but Steve Mitchell's idea of a raised water table may be one reason, their traditional haunts becoming flooded. We should not discount the idea that a more active sky, and changing climate, also provided the fuel to set them in motion. Various natural disasters are reported from the period, and enhanced meteoric and cometary activity.
The Votadini were not just allies of the Romans, they may actually have considered themselves to be Roman (as in Romanised), and were subsequently used as a buffer state between tribes further north and the new frontier at Hadrian's Wall. Formerly, the Votadini were safely within the geography behind the Antonine Wall.
The hill fort is therefore seen as important archaeologically as the Votadini, and other tribes in the Lowlands, were forced to defend themselves against the Pictish raids and expansionary activity. The Romans effectively abandoned this part of Scotland although there were several campaigns north of the Antonine Wall (in AD305, 368-9, and 384) and Stilicho campaigned against the Picts in AD400. After Britain dropped its ties with Rome a few years later the British tribes south of Hadrian's Wall were plagued by Picts raiding their lands and Angles were recruited as a mercenary army, ultimately leading to the establishment of the Kingdom of Northumbria. This was largely successful until a new group of raiders, the Vikings and the Danes, started to raid and plunder, leading to the overthrow of the Angles in Northumbria (and so on).