Under the Chinese Domination, the Tang Dynasty in China has put Vietnam (corresponding to the region of northern Vietnam today) An Nam (mean the south of China). Since then, what ever the official name is, they used to call Vietnam as Annam. This period Annam means the north of Vietnam now.
In the 19th Century, Vietnam was a French protectorate encompassing the central region of Vietnam. The region had a dual system of French and Vietnamese administration. The Nguyen Dynasty still nominally ruled Annam, with a puppet emperor residing in Hue. However, in substance, the entire government apparatus here are a French colonial official (Resident Superieur d'Annam – from Thanh Hoa to Nha Trang province) supervision and control.
Porte d'annam – Annam's door?
When the French approached to Annam (name of Vietnam at that time by The Chinese ) by boat, this country at that time was consider being the first entrance to see one of the new world.