Amborn Prasatthapong was born on 26 June 1927 at Mueang Ratchaburi, Ratchaburi Province to Nab and Tarn Prasatthapong, the second born of nine siblings. He was educated at Thewa Nukhro primary school in Lopburi. In 1937 he was ordained as a Samanera (or novice monk) at Wat Sattanat Pariwat in Ratchaburi. He studied the Pali language and graduated with a fourth level certificate in Pali studies in 1947.[1]
In 2009, he was presented with an honorary doctorate degree by Mahamakut Buddhist University. In 2010, he was presented with an honorary doctorate by Mahachulalongkornrajavidyalaya University.[2]
Ambaro was a student of the highly revered monk Phra Ajahn Fan Ācāro [th] a Vipassanā master and the former abbot of Wat Pa Udom Somphon in Sakon Nakhon province. Ambaro was practitioner of the Thai Forest Tradition of ascetic monks, which were known for their devotion to meditation and only eating once a day. In 1973, Ambaro joined a group of Dhammaduta (Thai: ธรรมทูต), or 'the messenger of the Dharma', on a trip to establish Thai Buddhism in Australia.[1]
In 2009, Ambaro was appointed abbot of Wat Ratchabophit, a royal temple of the first class, built in 1869 by King Chulalongkorn, where he has lived since 1948. On 5 December 2009, Ambaro was created the 2nd Somdet Phra Maha Muniwong (Thai: สมเด็จพระมหามุนีวงศ์) by King Bhumibol Adulyadej. This is a title given to a senior monk in the Dhammayuttika order.[1][3]
Supreme Patriarch
On 7 February 2017, Prime Minister Prayut Chan-o-cha confirmed the appointment of Somdet Phra Maha Muniwong as the 20th Supreme Patriarch of Thailand in a televised address. He succeeded Nyanasamvara Suvaddhana, the 19th Supreme Patriarch, who died on 24 October 2013 at the age of 100.[1] The prime minister stated: "I submitted the names of five qualified monks for His Majesty to consider. On Monday night, I was informed His Majesty chose Somdet Phra Maha Muniwong."[2]
Somdet Phra Maha Muniwong took the name Ariyavangsagatayana and became Somdet Phra Ariyavongsagatanana. On 12 February 2017, he was invested by King Vajiralongkorn in a ceremony at the chapel royal of the Temple of the Emerald Buddha.[1]