Why was the empire attacked by fierce tribes people? Tribes such as the Goths wanted to move south into parts of Europe that experienced a better climate that would assist their farming. This could only bring them into conflict with the Romans. At about AD 190, Rome also experienced a succession of poor emperors who simply were not capable of doing the job.
The Roman Army was spread throughout Western Europe. Each part of the army had its own idea as to who should be emperor. When one part of the army succeeded in putting its own man into the position of emperor, another part of the army would fight to put its own man in power. Between AD 211 and AD 284, there were twenty-three 'soldier-emperors' - and twenty of these men were killed by rivals! Clearly law and order and respect for that within Rome itself was at fault.
in AD 284, the emperor Diocletian realised that something had to be done or Rome and its empire would disintegrate. He decided to divide the Roman Empire in two to make it easier to rule - he created the Western Empire and the Eastern Empire, each with its own leader. This split geographically was all but a north to south divide between the empire with Spain, France, England, Italy and parts of Germany forming the Western Empire and all areas to the east of this were in the Eastern Empire.
However, Diocletian faced more than just administrative problems. More and more military defences had to be built across the whole empire. This cost money that Rome did not have. To pay for these, taxes were increased and extra coins were minted. This lead to inflation causing prices to rise. Therefore, the people of Rome were less than favourable towards those who led them.
With threats from tribes in northern Europe, financial problems in Rome itself and a civilian population becoming more and more discontented, Rome could ill afford further major issues.
In AD 307, Constantine became emperor. He ruled from AD 307 to AD 337. Constantine was Rome's first Christian emperor and he is considered to have been a strong ruler.
He believed that Rome as a city was too far away from vital