Question: Who was in charge in the country that is the natural boundary between the country that hosted the tournament and the country where That Dam is located?

Knowledge 1: 2020 AFC U-23 Championship qualification
Of the 47 AFC member associations, a total of 44 teams entered the competition. The final tournament hosts Thailand decided to participate in qualification despite having automatically qualified for the final tournament. [SEP] Knowledge 2: Vajiralongkorn Dam
Vajiralongkorn Dam (; ), also called the Khao Laem Dam (), is a concrete-faced rock-fill dam (CFRD) in Thong Pha Phum District in Kanchanaburi, Thailand. The dam lies across the Khwae Noi River (River Kwai) and was renamed Vajiralongkorn Dam after King Vajiralongkorn on 13 July 2001 when he was crown prince. Vajiralongkorn Dam is Thailand's first CFRD and supplies a 300 MW hydroelectric power station with water. The dam was built and is managed by the Electricity Generating Authority of Thailand (EGAT). [SEP] Knowledge 3: Geography of Myanmar
Myanmar (also known as Burma) is the northwestern-most country of mainland Southeast Asia, bordering China, India, Bangladesh, Thailand and Laos. It lies along the Indian and Eurasian Plates, to the southeast of the Himalayas. To its west is the Bay of Bengal and to its south is the Andaman Sea. It is strategically located near major Indian Ocean shipping lanes. [SEP] Knowledge 4: Myanmar
The impact of the post-election reforms has been observed in numerous areas, including ASEAN's approval of Myanmar's bid for the position of ASEAN chair in 2014; the visit by United States Secretary of State Hillary Clinton in December 2011 for the encouragement of further progress, which was the first visit by a Secretary of State in more than fifty years, during which Clinton met with the Burmese president and former military commander Thein Sein, as well as opposition leader Aung San Suu Kyi; and the participation of Aung San Suu Kyi's National League for Democracy (NLD) party in the 2012 by-elections, facilitated by the government's abolition of the laws that previously barred the NLD. As of July 2013, about 100 political prisoners remain imprisoned, while conflict between the Burmese Army and local insurgent groups continues.
Knowledge 1: That Dam
That Dam (Lao ທາດດຳ, meaning Black Stupa) is a large stupa located in Vientiane, Laos. Many Laotians believe it is inhabited by a seven-headed nāga who tried to protect them from an invasion by the Siamese army in 1827. [SEP] Knowledge 2: Geography of Myanmar
Myanmar (also known as Burma) is the northwestern-most country of mainland Southeast Asia, bordering China, India, Bangladesh, Thailand and Laos. It lies along the Indian and Eurasian Plates, to the southeast of the Himalayas. To its west is the Bay of Bengal and to its south is the Andaman Sea. It is strategically located near major Indian Ocean shipping lanes. [SEP] Knowledge 3: Myanmar
The impact of the post-election reforms has been observed in numerous areas, including ASEAN's approval of Myanmar's bid for the position of ASEAN chair in 2014; the visit by United States Secretary of State Hillary Clinton in December 2011 for the encouragement of further progress, which was the first visit by a Secretary of State in more than fifty years, during which Clinton met with the Burmese president and former military commander Thein Sein, as well as opposition leader Aung San Suu Kyi; and the participation of Aung San Suu Kyi's National League for Democracy (NLD) party in the 2012 by-elections, facilitated by the government's abolition of the laws that previously barred the NLD. As of July 2013, about 100 political prisoners remain imprisoned, while conflict between the Burmese Army and local insurgent groups continues. [SEP] Knowledge 4: 2020 AFC U-23 Championship qualification
Of the 47 AFC member associations, a total of 44 teams entered the competition. The final tournament hosts Thailand decided to participate in qualification despite having automatically qualified for the final tournament.
Knowledge 1: 2020 AFC U-23 Championship qualification
Of the 47 AFC member associations, a total of 44 teams entered the competition. The final tournament hosts Thailand decided to participate in qualification despite having automatically qualified for the final tournament. [SEP] Knowledge 2: Vajiralongkorn Dam
Vajiralongkorn Dam (; ), also called the Khao Laem Dam (), is a concrete-faced rock-fill dam (CFRD) in Thong Pha Phum District in Kanchanaburi, Thailand. The dam lies across the Khwae Noi River (River Kwai) and was renamed Vajiralongkorn Dam after King Vajiralongkorn on 13 July 2001 when he was crown prince. Vajiralongkorn Dam is Thailand's first CFRD and supplies a 300 MW hydroelectric power station with water. The dam was built and is managed by the Electricity Generating Authority of Thailand (EGAT). [SEP] Knowledge 3: Geography of Myanmar
Myanmar (also known as Burma) is the northwestern-most country of mainland Southeast Asia, bordering China, India, Bangladesh, Thailand and Laos. It lies along the Indian and Eurasian Plates, to the southeast of the Himalayas. To its west is the Bay of Bengal and to its south is the Andaman Sea. It is strategically located near major Indian Ocean shipping lanes. [SEP] Knowledge 4: That Dam
That Dam (Lao ທາດດຳ, meaning Black Stupa) is a large stupa located in Vientiane, Laos. Many Laotians believe it is inhabited by a seven-headed nāga who tried to protect them from an invasion by the Siamese army in 1827.

Answer: Thein Sein