I asked in a post below where the Đại Nam nhất thống toàn đồ (Complete Map of Unified Đại Nam) comes from. I see it a lot, and it is often referred to as dating from the 1830s, but I’ve never seen a source for this map. I’ve only found it reproduced in other works, such as the Nam Bắc Kỳ hội đồ (Illustrated Maps of the Southern and Northern Regions).
I finally decided to investigate this matter a bit and found that this map apparently appears in a 1929 work by P. A. Lapique called A Propos des Iles Paracels. Further, it apparently says below the map in that work that the map was extracted from the Hoàng Việt địa dư (Geography of the August Việt [Domain]) of the Minh Mạng era (1830s).
There are problems with this assertion, and some scholars have noted this. First of all, we have no evidence that the Hoàng Việt địa dư ever contained a map. Second, some of the terms on the map only came into use later. As a result, one discussion of this map that I read concluded that the map must date from some time between 1854 and 1875.
All of this is fine and logical, but there is one aspect about this map which I haven’t seen anyone address (though perhaps someone has mentioned this somewhere and I’m just not aware of it).
The Đại Nam nhất thống toàn đồ has the Mekong River running right though it, and the Mekong River wasn’t even explored until the late 1860s.
Further, in looking at (what I believe is) the first published full account of that expedition, Francis Garnier’s Voyage D’Exploration en Indo-Chine that was published in 1885, 12 years after Garnier’s death, I see that there is no map of the Mekong in this work.
So this made me wonder when the earliest map of the Mekong River appeared. I don’t have the answer yet, but one thing that I realize is that the Mekong started to appear on maps long before people actually understood it and were truly able to “map it.”
This 1764 map (Carte des royaumes de Siam, de Tunquin, Pegu, Ava Aracan, &c.) has the Mekong, but it’s not very accurate.
This one from 1780 (Les Isles Philippines, celle de Formose, Le Sud de La Chine, Les Royaumes de Tunkin. . .) is more accurate and realistic. But how did that happen? Did somebody go and map the region more accurately in the intervening years?
And then there is this one from 1864 (Map of the Burman Empire Including also Siam, Cochin-China, Ton-King, and Malaya. J…). This was created before the French Mekong expedition took off. This map represents the region in quite a bit of detail, and yet if you read the accounts of the expedition, the travelers got very confused at times about where they were.
Nineteenth-century Vietnamese maps also show the Mekong, but not very accurately.
This gets us back to the Đại Nam nhất thống toàn đồ. The one thing that is clear is that this is not a 100% “Vietnamese map.” Instead, I would argue that it is a “composite map” that combines together information from earlier Vietnamese and Western maps.
The detail with which the Mekong is depicted, appears to come from Western maps. And that line around islands also seems to have been inspired by a Western map, as you don’t see this on other Vietnamese maps (as far as I know).
What remains unclear to me is whether the Đại Nam nhất thống toàn đồ was based to some extent on a Western map that was made before or after the Mekong had been fully explored.
Given that Westerners had already made maps of the river before it had been fully explored, it is possible that the Đại Nam nhất thống toàn đồ could have been created between 1854 and 1875. Indeed, there was a serious effort in those years to produce geographical information about the kingdom.
If that is the case, however, then we have to be really suspicious about what it represents, and what the map makers actually knew.
If Westerners made maps without really knowing the territory, and if Vietnamese then made maps that were in part based on such Western maps. . . then to what extent can we say that these maps represent reality?