>>17784290
Originally the hair was tied up to help hold on a type of exaggerated tall court cap they liked to wear.
Then the head was shaved separately to deal with hair getting caught in helmets or getting gross on campaign - the Normans did something similar but basically in reverse to keep hair out of their mail coifs.
Then they started putting those together.
There was also a pretension of appearing older, as the hairstyle copied male pattern baldness, and made a man look older than he was. Age seniority is important in Confucian cultures.