Which empire never conquered areas of what is now Scotland?

The Romans were a powerful force in ancient Britain, establishing a presence that lasted for centuries. They built roads, towns, and forts across much of the island, leaving a lasting impact on its culture and infrastructure. However, their reach wasn't absolute. While they conquered and controlled much of what is now England and Wales, their attempts to subdue the northern part of the island, modern-day Scotland, were met with fierce resistance. The Romans ventured into Scotland several times, even building Hadrian's Wall to mark the northern boundary of their control. They also built the Antonine Wall further north, but it was abandoned after a short time. The tribes in the Scottish Highlands, particularly the Picts, proved too difficult to conquer. They used guerilla warfare tactics and the challenging terrain to their advantage. So, while the Romans certainly made incursions into Scotland, they never truly conquered and controlled it in the same way they did other parts of Britain. The other options, the Anglo-Saxons and Vikings, did establish settlements and exert influence in parts of Scotland during later periods. The Ancient Greeks, while influential in the Mediterranean, did not extend their empire to Britain.