Final answer:
Emperor Diocletian divided the Roman Empire into four sections, each under the control of a regional emperor. This system, known as the tetrarchy, provided a brief period of stability.
Step-by-step explanation:
During the third through fifth centuries, the Roman Empire underwent significant changes. In an attempt to restore stability, Emperor Diocletian divided the empire into four sections, each under the control of a regional emperor. This system, known as the tetrarchy, consisted of two senior emperors called Augusti and two junior emperors called Caesars. Each emperor had his own sphere of influence and a regional capital city. Diocletian's reforms and the tetrarchy provided a temporary period of stability for the Roman Empire.