Answer:
He split the Empire into two parts.
Step-by-step explanation:
Diocletian believed that the Empire grew so fast and it was so big that just one person couldn't control it. So, he split the Empire into two parts: Greek-speaking East (Greece, Anatolia, Syria, and Egypt) and the Latin-speaking West (Italy, Gaul, Britain, and Spain). Afterward, he would split into four parts, once the crisis and conflicts between the rulers obliged him to do so.