Six Provinces of Southern Vietnam

[1] The region was politically defined and established after the inauguration of the Nguyễn dynasty, and called by this name from 1832, when Emperor Minh Mạng introduced administrative reforms, to 1867, which culminated in the eight-year French campaign to conquer the Six Provinces.

[citation needed] In 1832, Emperor Minh Mạng divided Southern Vietnam into the six provinces Nam Kỳ Lục tỉnh.

According to the Đại Nam nhất thống chí (Nguyễn dynasty national atlas) of the Quốc sử quán (official Nguyễn-era compilation of Vietnamese history, geography and people from 1821 to 1945), in 1698 the lord Nguyễn Phúc Chu established the prefecture (phủ) of Gia Định.

[2] After the French colonial invaders, led by vice-admiral Charles Rigault de Genouilly attacked and captured the three eastern provinces of Gia Định, Định Tường, and Biên Hòa in 1862, and invaded the remaining western provinces of Vĩnh Long, An Giang, Hà Tiên in 1867, the French Empire abolished the administrative divisions created by the Nguyễn dynasty.

Following the 1899 decrees, starting 01/01/1900 Nam Kỳ would be divided into the following 21 provinces: The reason for this division into 21 provinces[4] was because the French Empire intended to erase the name "Lục tỉnh" from the hearts and minds of the Vietnamese people and language, and cut any feelings of attachment and Vietnamese nationalism with this region to avert potential local revolution or rebellion.

Southern Vietnam during the Nguyễn dynasty before 1841. Cần Vột ( Kampot ), Vũng Thơm ( Kampong Saom ) and Svay Rieng (triangular wedge protruding into Vietnam known as the "Parrot's Beak ") would later be ceded by French colonials to Cambodia . Cao Mien = Cambodia . Biển Đông = vi: East Sea . Nam Vang = Phnom Penh . Koh Kong was annexed by Siam until being returned to French Cambodia.
Map of Southern Vietnam in 1883 as part of French Indochina , however following the administrative divisions of the 1832–1862 Nguyễn dynasty's Nam Kỳ Lục Tỉnh .
Basse Cochinchine map
French Cochinchina (Basse Cochinchine Française) in 1881, based on the Nguyễn dynasty's Six Provinces before 1861. The northern bank of Vĩnh Tế Canal and the Parrot's Beak of Svay Rieng were ceded to the Cambodian Kingdom.