The Treaty of Perth ended military conflict between Norway under Magnus the Law-mender and Scotland under Alexander III over the sovereignty of the Western Isles, the Isle of Man and Caithness. The Treaty of Perth was agreed three years after the 1263 naval Battle of Largs. In Norwegian terms the Western Isles were known as the Sudreys (meaning Southern Isles) and they had become Norwegian territory during centuries when both Scotland and Norway were still forming themselves as coherent nation-states, and Norse control had been formalized in 1098, when Edgar of Scotland formally signed the islands over to Magnus III of Norway. Scotland also confirmed Norwegian sovereignty over Shetland and Orkney.

The Treaty of York (1237) defined the boundary between the two kingdoms as running between the Solway Firth (in the west at Cumbria's northern boundary along the border with Scotland to Northumberland) and the mouth of the River Tweed (in the east). It remains the border to this day, with the exception of a small area around Berwick, which was taken by England in 1482.

In January 1478, when Richard of Shrewsbury was about 4 years old, he married the 5-year-old Anne de Mowbray, 8th Countess of Norfolk. The two Princes in the Tower, Edward V of England (1470-1483) and Richard of Shrewsbury, 1st Duke of York (1473-1483?), were the two young sons of Edward IV of England and Elizabeth Woodville who were declared illegitimate by the Act of Parliament known as Titulus Regius. Their uncle, Richard III of England, placed them both in the Tower of London (then a palace as well as a prison) in 1483, and no one knows what happened to them after that, although they are presumed by many to have been killed there. Soon King Henry VII of England married Richard of Shrewsbury's eldest sister, Elizabeth of York. Elizabeth Woodville arranged to marry her daughter to Tudor. King Richard III at the Battle of Bosworth Field on August 22, 1485, was the last king from the House of York, and his defeat ended the Wars of the Roses and Tudor became King Henry VII. Wales had traditionally been a Yorkist stronghold, and Henry owed the support he gathered to his ancestry, being directly descended, through his father, from the Lord Rhys, kingdom of Deheubarth, South Wales. Rhys was probably born in Ireland.

Lady Eleanor Talbot (died 1468) was a daughter of John Talbot, 1st Earl of Shrewsbury who was an important English military commander during the Hundred Years' War. Her alleged pre-contract of marriage with King Edward IV of England was of great significance to the final fate of the Plantagenet (Angevin) dynasty. Angevin is the name applied to the residents of Anjou, a former province of the Kingdom of France but later came to rule far greater areas including England, Ireland, Hungary, Poland, Naples and Sicily, and Jerusalem. The Angevin Empire is a modern term applied retrospectively to the lands of Henry II of England. In 1449 or 1450, Eleanor married Sir Thomas Butler (son of Ralph Butler, Lord Sudeley), who died some time before March 1461. Lady Eleanor Butler died in a convent in June 1468 and was buried in the Church of the White Carmelites, Norwich, England. Some years later, the priest in question (Commynes is the only source who identifies him as Stillington) is said to have told King Edward's unstable and untrustworthy brother, George, Duke of Clarence, about the pre-contract. Clarence was already on the verge of rebellion against his elder brother; Edward now threw both his brother and Stillington into the Tower of London.

With the Treaty of York, Alexander II abandoned traditional Scottish claims to the regions of Northumbria, south of the Tweed, and Cumbria (NW England with parts of Hadrian's Wall in and around Carlisle). Northumbria had history, predating the competing claims of England and Scotland, as a kingdom strethching from the Humber to the Forth. But the Fens are an area of former wetlands in the counties of Cambridgeshire, Lincolnshire and Norfolk in eastern England. The fenlands are a silted-up bay of the North Sea that embraces the lower drainage basins of the rivers Witham, Welland, Nene and Great Ouse.

In the Anglo-Saxon period, the Humber estuary was a major boundary, separating Northumbria from the southern kingdoms. Indeed the name Northumbria simply indicates the area North of the Humber. It currently forms the boundary between the East Riding of Yorkshire, to the north and North and North East Lincolnshire, to the south. The North Wall called Humberside runs for several miles along the banks of the river Humber. Alexander II abandoned traditional Scottish claims to the counties of Northumbria and Cumbria. This treaty secured England's northern border.