The Art of Late Antiquity

How does the Portrait of the 4 Tetrarchs reflect the cultural and stylistic significance of the Late Imperial period? (Be specific with your dates). Describe the piece. What does their body language reveal about their approach to ruling the empire?
What was the Tetrarchy?
Why was it necessary? Who was Diocletian?
How does the Portrait of the 4 Tetrarchs reflect its cultural context? (political, social, cultural, religious ideas)
How does the Portrait of the 4 Tetrarchs reflect the stylistic shift evident in Late Imperial / Late Antiquity period?