Question: What year did the country where Pao Sarasin was born form an alliance with Japan?

Knowledge 1: Pao Sarasin
Pao Sarasin died at Siriraj Hospital in Bangkok after a month-long hospitalization for a blood infection on March 7, 2013, at the age of 83. A royal bathing rite ceremony for Sarasin was held at the Wat Benchamabophit with Princess Maha Chakri Sirindhorn in attendance representing the royal family. He was survived by his wife, Thapuying Tawika Sarasin, and three sons, including Thai television host, Kanit Sarasin. [SEP] Knowledge 2: Pacific War
The Axis states which assisted Japan included the authoritarian government of Thailand in World War II, which quickly formed a temporary alliance with the Japanese in 1941, as the Japanese forces were already invading the peninsula of southern Thailand. The Phayap Army sent troops to invade and occupy northeastern Burma, which was former Thai territory that had been annexed by Britain much earlier. Also involved were the Japanese puppet states of Manchukuo and Mengjiang (consisting of most of Manchuria and parts of Inner Mongolia respectively), and the collaborationist Wang Jingwei regime (which controlled the coastal regions of China). [SEP] Knowledge 3: Bang Bon District
Bang Bon (Thai: บางบอน, pronounced [bāːŋ bɔ̄ːn]) is one of the 50 districts (khet) of Bangkok, Thailand. Its neighbours, clockwise from north, are Bang Khae, Phasi Charoen, Chom Thong, and Bang Khun Thian districts of Bangkok, Mueang Samut Sakhon District and Krathum Baen District of Samut Sakhon Province, and Nong Khaem District of Bangkok.
Knowledge 1: Pao Sarasin
Pao Sarasin died at Siriraj Hospital in Bangkok after a month-long hospitalization for a blood infection on March 7, 2013, at the age of 83. A royal bathing rite ceremony for Sarasin was held at the Wat Benchamabophit with Princess Maha Chakri Sirindhorn in attendance representing the royal family. He was survived by his wife, Thapuying Tawika Sarasin, and three sons, including Thai television host, Kanit Sarasin. [SEP] Knowledge 2: Pacific War
The Axis states which assisted Japan included the authoritarian government of Thailand in World War II, which quickly formed a temporary alliance with the Japanese in 1941, as the Japanese forces were already invading the peninsula of southern Thailand. The Phayap Army sent troops to invade and occupy northeastern Burma, which was former Thai territory that had been annexed by Britain much earlier. Also involved were the Japanese puppet states of Manchukuo and Mengjiang (consisting of most of Manchuria and parts of Inner Mongolia respectively), and the collaborationist Wang Jingwei regime (which controlled the coastal regions of China). [SEP] Knowledge 3: San Sali
San Sali () is a village and "tambon" (subdistrict) of Wiang Pa Pao District, in Chiang Rai Province, Thailand. In 2005 it had a total population of 9051 people. The "tambon" contains 13 villages.
Knowledge 1: San Sali
San Sali () is a village and "tambon" (subdistrict) of Wiang Pa Pao District, in Chiang Rai Province, Thailand. In 2005 it had a total population of 9051 people. The "tambon" contains 13 villages. [SEP] Knowledge 2: Pacific War
The Axis states which assisted Japan included the authoritarian government of Thailand in World War II, which quickly formed a temporary alliance with the Japanese in 1941, as the Japanese forces were already invading the peninsula of southern Thailand. The Phayap Army sent troops to invade and occupy northeastern Burma, which was former Thai territory that had been annexed by Britain much earlier. Also involved were the Japanese puppet states of Manchukuo and Mengjiang (consisting of most of Manchuria and parts of Inner Mongolia respectively), and the collaborationist Wang Jingwei regime (which controlled the coastal regions of China). [SEP] Knowledge 3: Pao Sarasin
Pao Sarasin died at Siriraj Hospital in Bangkok after a month-long hospitalization for a blood infection on March 7, 2013, at the age of 83. A royal bathing rite ceremony for Sarasin was held at the Wat Benchamabophit with Princess Maha Chakri Sirindhorn in attendance representing the royal family. He was survived by his wife, Thapuying Tawika Sarasin, and three sons, including Thai television host, Kanit Sarasin.

Answer: 1941