The website amphoe.com was a very helpful resource in creating the district articles on Wikipedia, as it contains several pages for each district, including things like the address of the district office, the slogan of the district, and most of all the history of the district. In some case its a quite long history starting with the precursor Mueang, in other cases just a the basic dates of creation as a minor district and upgrade to a full district. However sadly the site is far from perfect, I have came across several cases where the history is somewhat sloppy - for example listing the date the announcement in the Royal Gazette was published or signed, not the date when it became effective - but in a few cases it seems to have been outright wrong, even noticeable with my limited knowledge on the Thai language. Especially with the renamings of districts to historical names, or name switching like the one I blogged about earlier they easily get it wrong.
One example is the history of Renu Nakhon, where amphoe.com says that in 1917 the district Renu Nakhon was reduced to a subdistrict of That Phanom district. But in real it was simply that the district was renamed from Renu Nakhon to That Phanom.
Another item which I can easily check is the area of the district. I used the value given in the Census 2000, and in most cases amphoe.com gives exactly the same value. In several cases it even has higher accuracy, in the census data it's just up to 0.1 km², while in those cases it's down to 0.001 km². But in other cases the value is slightly off, or even very much off. Sometimes I could notice the value still included a minor district already split off, sometimes it was the value in Rai but with the wrong unit name, but sometimes it was really completely bogus.
It seems to me that when creating amphoe.com the province administrations were asked to provide the informations, some did a really good job while other did it only sloppy. It's not much different with the websites of the province administrations itself, some are very elaborated with regards of history, while others have nearly no useful data.
Wikipedia now has a policy of giving references for each of the claims in the article. Too bad I cannot use amphoe.com as such with good conscience anymore, and they don't give their sources either for further check. And often the text found at amphoe.com is copied by several other websites, and no other independent history is found on the web, at least none I could find and read. At least quite a lot of the references can be done with the help of the Royal Gazette search, but that still makes the district histories rather short, as just the administrative changes to the districts are covered by this.
But even worse - the website was apparently hacked for quite some time by some spammer or malware distributor (at least the GoogleBot has already indexed it). When using the bare http://www.amphoe.com it redirects to some sites I wouldn't recommend anyone to follow with Internet Explorer and without an up-to-date virus scanner. As usually used the bookmark (which had the a main.php) I did just notice this a few days ago, but even after I sent a warning email to the administrators nothing happened :-(
Update January 3: Now they have fixed the hacked webpage.