Emperor Diocletian ruled the Roman Empire from 284 to 305 AD. He is best known for his significant reforms that helped stabilize the empire after a period of crisis. Diocletian divided the empire into four regions, each governed by a co-emperor, to improve administration and defense. Diocletian also implemented economic reforms, including price controls and tax adjustments, to combat inflation and improve the economy. His reign marked the beginning of the Dominate, a more autocratic form of government, and he is often credited with laying the groundwork for the later Constantinian reforms.