Complex sentence: It is also noted that Porphyrius had monuments built in his honor by both the Greens and the Blues, testimony to the fact that he was admired and sought after for his great chariot skills.
Split into simpler sentences: It is also noted that Porphyrius had monuments built in his honor by both the Greens and the Blues. Further supporting the fact that he was admired and sought after for his great chariot skills.