Boriwen in Monthon Udon Thani

One administrative subdivision I don't know much about are the boriwen (บริเวณ, regions), which existed during the thesaphiban reforms in the beginning of the 20th century. So far, all I knew were these few sentences in Tej Bunnag's The provincial administration of Siam, 1892-1915

But since this still left vast areas with hardly any supervision, the monthon was subdivided into three administrative areas (boriwen) which were placed under area commissioners (khaluang boriwen). For the same reason, the north-eastern provinces were grouped into ten administrative areas which were divided equally between monthons Udon and Isan.

and a bit later

The new districts and communes in monthons Phayap, Udon and Isan were amalgamated into the administrative areas (boriwen) which had been created in 1900 and 1901. In 1907, the fact that Pattani, Yala and Saiburi and the administrative areas were going to become new provincial units was emphasized by their being given the new name of changwat.

and in the appendix it also gives a list of these regions with the towns under them. In fact, I wasn't aware of the second quotation until I recheck my scans of that book now.

The reason I did this was that I now first found the first trace of these entities in the Royal Gazette as well. While there are a lot of announcements with the word บริเวณ, none of them seems to refer to these entities mentioned above. But when I now worked through an announcement on the mueang in monthon Udon Thani published on January 12 1908. This includes the merge of four Mueang to form the new Mueang Udon Thani, the precursor of the modern-day province Udon Thani, mentions the two unchanged Mueang Nong Khai and the (later abolished) Phon Phisai, but most interestingly four entities which were previously Boriwen and now became Mueang:

• Boriwen Nam Chi (น้ำชี) becomes Mueang Khon Kaen
• Boriwen Nam Hueang (น้ำเหือง) becomes Mueang Loei
• Boriwen Sakon Nakhon becomes Mueang Sakon Nakhon
• Boriwen That Phanom (ธาตุพนม) becomes Mueang Nakhon Phanom

Sadly the announcement does not list the subdivisions - the appendix in Bunnag's book gives the Boriwen of Udon Thani as follows:

• Boriwen Makkhaeng consisting of Ban Makkhaeng (Udonthani), Nongkhai, Nonglahan, Kumphawapi, Kamutthasai, Phonphisai, and Rattanawapi
• Boriwen Phachi consisting of Khonkaen, Chonnabot, and Phuwiang
• Boriwen That Phanom consisting of Nakhon Phanom, Chaiburi, Tha Uthen and Mukdahan
• Boriwen Sakon consisting of Sakon Nakhon
• Boriwen Nam Huang consisting of Loei, Kaen Thao, Bo Tha

The two don't fit completely - Sakon is named Sakon Nakhon, and Phachi is Nam Chi; also the Boriwen Makkaeng isn't mentioned at all, and of the seven subdivisions Rattanawapi isn't mentioned at all, while Nong Khai and Phon Phisai continue to be at provincial level.