From the incident of R.S.112 when France sent 3 warships to block the mouth of the Chao Phraya River on July 13, 1893, King Chulalongkorn had to give up the land on the left bank of the Mekong River to France according to the “Treaty between Siam and France on October 3, R.S.112”. From the said treaty, Chiang Khan, which used to rule the communities on both sides of the Mekong River, was divided into 2 parts: the east bank or the left bank was under the control of France, and the right bank on the west bank, which was the center of the city at that time, was still under the control of Siam. After losing the area of ​​Chiang Khan on the left bank of the Mekong River to France, France tried to persuade Phra Sri Arkhahat (Thongdee), the governor of Chiang Khan, to bring the people across the Mekong River to be under the control of France, but was rejected. Therefore, France tried to find a reason to slander Phra Sri Arkhahat (Thongdee) and the Chiang Khan city officials by sending complaints to the Bangkok Royal Court continuously. However, the Bangkok court still believed in the loyalty of Phra Sri Arkhat (Thongdee) and his family. Although France had already obtained Lao territory on the left bank of the Mekong River, in 1902, France discovered that the influence of the Luang Prabang court was actually on both banks of the Mekong River. The right bank extended to Nan Province, claiming that the King of Luang Prabang had previously ruled the area. Therefore, they wanted to redefine the borders of Luang Prabang. This led to the signing of a new treaty in 1902, in which Siam had to cede the area on the right bank of the Mekong River between Luang Prabang and Phichai down to the Hueang River to be under French rule. Some of the people of Chiang Khan who still built their homes at the mouth of the Hueang River on the right bank and did not want to be under French rule moved their households to Ban Thana Chan (currently the location of Chiang Khan District). Meanwhile, some of the people chose to cross over to live in the plains along the valley on the right bank of the Hueang River, which developed into a large community today. After the signing of the Convention of R.S. 121, France continued to try to influence Chiang Khan by signing a land lease agreement for navigation in early B.E. 2450. This convention was called “The Convention between Siam and France on the Permission of Land on the Right Bank of the Mekong River According to the Agreement of February 13, B.E. 122” until France withdrew from Laos and various treaties were revised. The leased area in Chiang Khan became an empty area. The Siamese government then used it as a government center until today. Phra Si Arakhat (Thongdee) ruled Chiang Khan continuously until B.E. 2442 when he was promoted to “Phraya Si Arakhat”, which seemed to be a special case because normally, the position of the vassal city governor of a large provincial city usually has the title only “Phra”, while the vassal city governor is of the third class. And the second-class provincial towns would have the title of “Phraya”. The promotion to this title at that time was considered the highest honor that Phraya Si Arakhat (Thongdee) received from the royal grace of King Rama V. Later in 2450, the Ministry of Interior announced the unification of the towns in Udon Thani Province into the fourth-class cities on January 12, 2450 as appeared in the Royal Gazette that the towns which were originally called Nam Hueng area were to be renamed “Muang Loei” and had the status of a province under Udon Thani Province. Chiang Khan City, which is near Loei City, is another city that the Ministry of Interior wanted to transfer the administration from Phitsanulok Province to Udon Thani Province. However, it had been delaying all along out of respect for Phraya Si Arakhat (Thongdee), who was honest and loyal and had done good for the Bangkok court since before. Moreover, in the past, in the management of the Thesaphiban Province, His Majesty King Chulalongkorn specifically ordered that: “...Phraya Si Arakhat is an honest person. No matter what kind of governance you have, please do not let it be a cause for trouble for Phraya Si Arakhat. It has always been like this...” However, after King Chulalongkorn passed away in 2453, Phraya Si Arakhat (Thongdee) himself was very old. The administration was therefore in the hands of his children and grandchildren. The Ministry of Interior saw that it was time to re-administer Chiang Khan for the benefit of public administration. Chiang Khan was moved to be under the jurisdiction of Loei Province in 2454, causing Chiang Khan to be downgraded from “Chiang Khan City” to “Chiang Khan District”. Phraya Si Arakhat (Thongdee), the governor of Chiang Khan, was changed to “Governor of Chiang Khan District”, which is the same position as the current district officer. Even though before that, he had received a royal warrant to be the governor of the city. Another page of history therefore recorded that Phraya Si Arakhat (Thongdee) was the last person to hold the position of governor of Chiang Khan. And he was the first district officer of Chiang Khan. Phraya Si Arkhat (Thongdee) held the position of governor of Mueang Chiang Khan for 2 years and passed away on June 23, 1913 at the age of 70. King Rama VI granted a coffin for the cremation of Phraya Si Arkhat (Thongdee) on September 15, 1913. On this occasion, he also granted 1,000 satang and 2 folds of white cloth along with the coffin. This concluded the story of Chiang Khan, which had long progressed from being a city in a traditional state system until it completely transformed into a modern state.