Shi Xiaobai had a dream.
A very, very long dream.
In his dream, he was a king of a territory. He led his troops in a long war, going from one end of a continent to the other while constantly forging ahead. He conquered one country after another. When he conquered more than half, and was about to complete the feat of ruling over an entire continent, fiends of an alien world suddenly invaded. Immediately, he led his troops to face the invading fiend legion.
It was similarly a long battle, much longer than his conquest wars and much more brutal and bloody. Humans perished in great numbers but he finally succeeded in chasing the fiend legion back to the alien world.
After that battle, every country put a stop to all wars to prevent the invasion of the fiend legion or other species of alien worlds. As such, Shi Xiaobai's ambition of conquering the entire continent had to come to a stop.