Acai, chief of Tu Gu Hun, had 20 sons. One day A'cai said to them:

"Do you know the reason behind? A single arrow can be easily broken, but assembled together, the arrows will be hard to destroy. As long as you work in full cooperation and with unity of purpose, our throne will be passed down from generation to generation."

"Bring an arrow and break it."

Then, he broke the arrows one by one and threw them on the ground.

After a while, A'cai said to Mu Liyan, his half-brother by the same mother:

Mu Liyan broke the arrow without any effort.

"Each one of you bring me an arrow."

Tu Gu Hun in ancient times is now the Song Pan area of Qinghai and Sichuan Provinces.

"Bring 19 arrows and break them together," demanded A'cai again.

But this time Mu Liyan couldn't make it despite all his efforts.

Thereupon, Acai said meaningfully: