Districts and provinces in the deep south around 1909

My post on the administrative history of Pattani has found at least one reader very interested into the topic. He has even digged out an old map dating from the time of the 1909 boundary treaty between Siam and the United Kingdom fixing the boundary the way it still is today.

Of the five points he stumbled upon in this map, I can at least answer some relatively easy with the sources available to me.

• Tak Bai belonged to Kelantan before 1909, but as the Sungai Kolok river was chosen as the boundary line, the area of Tak Bai district stayed under Thai control. In August 1909 the creation of the district under the province Narathiwat was announced in the Royal Gazette.
• The same Gazette announcement also includes the creation of Sadao district by merging together the subdistrict Sadao with the minor district Prink (กิ่งปริก), which was a subordinate of Nuea district (now named Hat Yai). Originally, Sadao belonged to Changlun and was part of the ''Mueang'' Saiburi, better known as Kedah. Due to the 1909 contract Changlun became Malay, while the northern part of it became Thai and thus was made the district Sadao. Strangely the history of the district in amphoe.com must be wrong, as that claims the district was created in 1917, and at the same time the subdistrict was renamed from Changlun to Sadao. Yet the Gazette announcement dates it to 1909, and also does not mention the name Changlun at all. As the Wikipedia article was originally based on amphoe.com this researched could at least fix the history in there.
• Thepha was drawn as a separate province in that map, which must be a misunderstanding of the mapmaker. Here amphoe.com gives a detailled history, according to which Thepha was a forth-class Mueang and subordinate of Phatthalung in 1786, when the governor of Thepha had to present the tribute as a golden and silver tree to the governor of Phatthalung. In the reign of King Rama II it was upgraded to third-class Mueang and placed under Songkhla. But no trace of the alleged reassignment of this district from Pattani to Songkhla as it was claimed by the anonymous Wikipedia editor.
• Also Chana was drawn separately. As the website of the district (there are only very few districts with a website, and this is a very good one) has a long history text including a list of all the past governors and district officers. This history is quite similar with Thepha, as Chana also was at first a subordinate of Phatthalung and then became reassigned to Songkhla. The town was moved around often - last location was in Pa Ching subdistricy before the district was created in the thesaphiban reforms. The first district office was in present-day Na Thawi district, but since the location was inconvenient it was moved to Ban Na, and the district was renamed to Ban Na then. While the website gives no date, the rename was announced in 1917 in the Gazette. In 1924 the name change was reverted, as there were two more districts with the same name already.
  

The two things I cannot answer is the fact that Perlis is shown divided into two entities, and Raman and Rangae's extent into current Perak and Kelantan respectively. The Wikipedia article on Perlis does not mention any division, but the second one I can at least suspect that it might be similar to the above mentioned case of Sadao and Tak Bai where the 1909 boundary does not follow the historical boundaries of the Mueang.