<human>:  When did the Romans stop using the legion?
<bot>: The Roman legion was a large, well-trained, and well-equipped army. It was used by the Romans from the time of the Roman Republic until the end of the Roman Empire. The legion was a very powerful military force, and it was used to conquer many different countries. The legion was a very important part of the Roman military, and it was used to defend the Roman Empire.