After reaching its maximum extent under Trajan, the Roman Empire began a gradual decline from 117 CE onwards. Lowland Scotland between Hadrian’s Wall and the Antonine Wall was abandoned as a permanent area of settlement around 185 CE because the resources needed to defend the area outweighed the benefits. Similarly, the northern regions of the Netherlands behind the main frontier had been subject to Roman influence and trade but were abandoned once the empire began to weaken. Dacia was part of the old Dacian Kingdom which was conquered under Trajan. Whilst under Roman rule it enjoyed technological advancement, however after a small expansion it eventually fell back into the hands of Dacian tribes. Britain was abandoned from the late 4th century onwards as military units were needed elsewhere in the empire and Roman officials were eventually expelled. Theodosius ceded Pannonia to the Huns in the mid-5th century.
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