Annam (安南; pinyin: Ānnán) or Jiaozhi (交趾; pinyin: Jiāozhǐ; Vietnamese: Giao Chỉ) was the southernmost province of the Chinese Empire. It is now part of present-day Vietnam.[1] The region roughly corresponds to the area known as Tonkin.
In the 2nd century BCE, what later became Annam was part of the kingdom of Nan Yue or Triệu Dynasty, an ancient kingdom formed upon the union of Baiyue people at the final collapse of the Qin Dynasty by former Qin General Zhao Tuo and was nominally subject to the Chinese Han Empire. In 111 BCE, the Han imperial government, under Emperor Wu of Han, invaded Nanyue and asserted direct control for the first time. By 108 BCE, the conquest was completed and the Chinese took over the lands. The first name given the land based around Hanoi and the Red River was Jiaozhi. In 679, Tang Dynasty established Protectorate General to Pacify the South (Chinese: 安南都护府) as their military government in Jiaozhi. The Sino-Vietnamese name of this government is An Nam đô hộ phủ which can be called for short An Nam (Pacified South) or Annam as in Western documents.
It was to remain Annam for the next 600 years, seemingly living up to its name. A peaceful territory, part of a succession of Chinese kingdoms: Wu, Eastern Jin Dynasty, Song, Southern Qi, Liang, Chen, Sui Dynasty, and the Tang Dynasty. However there were still revolts from time to time and periods of weaker government control.
Finally in 939, Ngo Quyen successfully expelled the Chinese at the battle of Bach Dang river where he beheaded the Commanding Admiral and Prince of Southern Han Dynasty, Liu Hung-ts'ao and re-established the independent state of Dai Viet. This was the effective end of Annam as a Chinese province. Several attempts were made by various Chinese governments to retake Vietnam, one succeeded (Ming Rule of Vietnam) but only for 20 years (1407 - 1427).
In the 1860s, the French government under Napoleon III conquered first southern and then central Vietnam. The central portion of the country they ruled as the protectorate of Annam.