Red:

Red was also a badge of rank. During the Song dynasty (906–1279), officials of the top three ranks wore purple clothes; those of the fourth and fifth wore bright red; those of the sixth and seventh wore green; and the eighth and ninth wore blue. Red was the color worn by the royal guards of honor, and the color of the carriages of the imperial family. When the imperial family traveled, their servants and accompanying officials carried red and purple umbrellas. Of an official who had talent and ambition, it was said "he is so red he becomes purple."

Please answer a question about this article. If the question is unanswerable, say "unanswerable". What color did sixth rank Song dynasty officials wear?
green