In the article Tradition and cultural background of the Patani region by Worawit Baru (วรวิทย์ บารู) alias Ahmad Idris (in: Regions and National Integration in Thailand, 1892-1992), the author starts to give a short historical background of the region. This ends with the following
After the transformation from absolute Monarchy to Democracy in 1932, Saiburi which used to be a cangwat was incorporated as an amphoe (district) into Cangwat Pattani (Nanthawan 1978:9).This however is at best an overly simplification, or just wrong, because the province Saiburi wasn't changed into a district and placed into Pattani. In fact, since the administrative structure was established all over the country in about 1910, in every case an administrative entity was abolished this meant that the subdivision of the entity were reassigned to a new parent, and not that the entity was reduced in status. The only downward status change was district (amphoe) to minor district (king amphoe).
Thus in the case of Saiburi, the announcement from 1932 says
๗. ให้ยุบเลิกจังหวัดสายบุรี รวมท้องทีเข้าไว้ใน ปกครองของจังหวัดปัตตานี เว้นแต่ท้องที่อำเภอบาเจาะ ให้ยกไปขึ้นอยู่ในปกครองของจังหวัดนราธิวาสThus the southern half of the province, i.e. the district Bacho, came to Narathiwat, while the district Saiburi together with the minor district Kalapho (กิ่งอำเภอกะลาพอ) came to Pattani. As a minor district is a partial subordinate of a full district, counting Kalapho and Sai Buri as a single district is at least not totally wrong, but Bacho was definitely left out in the above statement.
To abolish the province Saiburi add area to govern by Pattani province except Bacho district, which is separated to be governed by Narathiwat province
I don't know whether the mistake was done by the author of the above paper, or already exists in the cited source (Nathawan Phusawong, ปัญหาของชาวไทยมุสลิมในสี่จังหวัดภาคใต้, Paper presented at The Social Sciences Association of Thailand, 1978) as I have no access to that one; but it can simply serve as an example that one always needs to check several sources, as even academic papers can contain mistakes.
In the map I have tried tried to give an idea of the extend of the province, note however that the boundaries are those as of today, so transfers of villages or subdistricts (though I am not aware of any) might have changed the boundary. It also only shows the extend at the abolishment, the districts Yi-ngo and Mueang Narathiwat were part of the province till about 1909. I also could not add the minor district Kalapho in the map - according to the Taluban municipality website the minor district became the subdistrict Tro Bon (same problem as above, it probably should say the minor district only comprised the subdistrict Tro Bon at its abolishment), and I only know the subdistrict Bue Re to be split off from Tro Bon - but since the minor district was in the northwestern corner it should at least also include the subdistricts Thung Khla, otherwise the boundary looks to strange. Sadly, the announcement on the abolishment of the Kalapho does not say anything about the subdistricts within the minor district.