Zhafa year means: the age of adulthood, that is, the age of boys 15 years old. A bundle of hair is a bundle of hair. Before the Qing Dynasty, when Han boy 15 years old, his hair was tied in a bun and he became an adult. When you are 20 years old, you will be crowned an adult. So that bundle of hair refers to the age of adults, that is, 15 years old.

In ancient times, boys could go to college when they were in their prime. The book "Fu Bao" says: "Go to college with your hair tied, learn great art, and complete great festivals."