When creating the legislative branch, representation was an issue that was argued over constantly. The small states, like New Jersey, wanted all states to have the same representation regardless of their states population. However, big states like Virginia wanted states with more population to have more power. These two sides come to a compromise (called the Connecticut Compromise) which states that the amount of representatives in the House will be based on population while every state will have 2 senators in the Senate.
Attacks from barbarian tribes outside of the empire such as the Visigoths, Huns, Franks, and Vandals. In 285 AD, Emperor Diocletian decided that the Roman Empire was too big to manage. He divided the Empire into two parts, the Eastern Roman Empire and the Western Roman Empire.