What does the pacified south mean?

The Pacified South is known as Annam, which is a province in China.

Explanation:

Annam (Vietnamese form of Annan, a Chinese name) means "the Pacified South" or "to Pacify the South". It was the southernmost province after the Tang dynasty.

Pacified: to bring or restore to a state of peace or tranquillity; quiet; calm basically it means to appease: to pacify one's appetite like to reduce to a state of submission, especially by military force; subdue ect.