Cochinchina (Indochina)

The Cochinchinese flag that shown is a late XIXth century flag. As you know, the Indochinese Union was made of 5 entities: 1 colony (Cochinchina) and 4 protectorates (Tonkin, Annam and Paracel Islands, Cambodia, Laos). Is this flag the official flag of the Colony of Cochinchina? Does anyone know something about a Tonkinese flag during French rule?
Pierre Gay, 13 December 1998

The Cochinchina flag was in fact an ensign. Seems that was an older ensign of the Annam Emperors: yellow (as China) with serrated ribbon. The serrated ribbon seems to be wrong interpreted from far observation or descriptions, and converted in many triangles (they are reported somewhat as grey-blue, green, maroon, and black; and now in blue). But after the establishment of the protectorate the ensign was little (or never) used in Cochinchina, and disappeared also in Annam before c. 1885. Afterwards, there was no flag for Cochinchina colony (like no flag for French colonies). Tonkin was a vice-kingdom of Annam. Perhaps the viceroy used his own standard but that is not know for me. I believe that no specific flag for Tonkin was never reported.
Jaume Ollé, 13 December 1998

Cochinchina originally appears to have referred to the area between India and China, not to a specific location. A flag similar to the Cochinchina flag (it appears to have a dragon in the center) is depicted in a black and white picture engraving on a University of Richmond website dealing with Vietnam in particular about the Trung sisters who led a rebellion against the Chinese between 39-40 AD. However given the fact that the script on the image is the current script and not the Chinese-style script, it is unlikely to verify the flag would have been used during the Trung rebellion, rather a depiction using a more modern symbol - and the Trung sisters would be used as inspiration in the battles for independence against the French and the fight against the Americans. Unfortunately no date is given for the origin of the picture.
Phil Nelson, 1 September 2003