The Gask Ridge is the modern name given to an early series of fortifications, built by the Romans in mid-Scotland.
It was constructed in the 70s or 80s CE. Hadrian's Wall was built 40 years later and the Antonine Wall 20 years after that. Although the border was not a continuous wall, it may well be Rome's earliest fortified land frontier.
The fortifications cover the boundary between Scotland's mountainous Highland zone in Perthshire and Angus, protecting the more fertile land to the South and East. The later Hadrianic and Antonine walls were further south, and, by taking advantage of Britain's heavily indented coastline, were considerably shorter.
The Gask Ridge consisted of a series of forts and fortlets with signalling towers. The Legionary fortress of Inchtuthill and other forts nearby are collectively referred to as the Glen Forts. The relationship between the Glen Forts and the Gask Ridge is unclear.
Tacitus writes that Agricola was fighting in the area in 80 CE. The latest coinage dates from 86 CE. This would suggest that the forts were occupied for at most 6 years. However, recent archaeology has shown that many of the forts comprising the Gask Ridge were rebuilt over time, sometimes twice, without any evidence of destruction through warfare. Further digs may cast some light on this apparent contradiction.
External links
http://www.morgue.demon.co.uk/Pages/Gask/index.html