The Late Roman Empire refers to the period from the 3rd century to the fall of the Western Roman Empire in 476 AD. This era was marked by political instability, economic decline, and military challenges. The empire faced invasions from various groups, including the Goths and Vandals, which weakened its borders and resources. During this time, significant reforms were implemented, such as those by Emperor Diocletian, who divided the empire into smaller regions for better management. The rise of Christianity also transformed the cultural landscape, leading to the establishment of the Byzantine Empire in the east after the fall of the west.