by the Roman Catholic Church), to start the work of evangelization in Chiang Mai. They reached Chiang Mai on 18 January 1931 and stayed with the Desousa family. Their work spread the Catholic faith. Missionary activities in other provinces also started to bear fruit in the 1930s. The 1950s and 1960s were decades of progress in spreading the Catholic faith. Various congregations initiated missionary activities. A number of Catholic schools and churches were built while parishes and areas of apostolate and pastoral work were defined. On 17 November 1959, the northern region mission was erected as the Apostolic Prefecture of Chiang Mai with Bishop Lucien Lacoste as its first bishop and head of the local church. The Apostolic Prefecture of Chiang Mai was elevated into a diocese on 18 December 1965. After the resignation of Bishop Lucien Lacoste on 14 September 1975, Bishop Robert Rattana Bamrungtrakul was installed as the head of the Diocese of Chiang Mai. Bishop Joseph Sangval Surasarang was installed in the office as the head of the diocese on 25 January 1987. At present, the entire Diocese of Chiang Mai is under the leadership of His Excellency Bishop Francis Xavier Vira Arpondratana, who received his episcopal ordination on 1 May 2009. Until 2018 Chiang Mai Diocese included eight provinces: Chiang Mai, Chiang Rai, Lamphun, Lampang, Phayao, Phrae, Nan, and Mae Hong Son. Of a total population of 5.7 million, the number of Catholics has grown to 68,975 along with 15,080 catechumens who are preparing themselves to receive the sacrament of baptism. Ninety-four priests, 16 religious brothers, 153 nuns and 151 catechists are at work in the diocese. Over the years, 518 chapels were built in the diocese's 47 parishes. Serving as the seat of the Catholic missions in the northern region of Thailand, the entire diocese covers a total land area of 85,852 square kilometers covering all eight Northern provinces: Chiang Mai, Chiang Rai, Nan, Phayao, Phrae, Mae Hong Son, Lampang and Lamphun. In 25 April 2018 from the territory of the diocese was spring off the new circumscription, the Roman Catholic Diocese of Chiang Rai. Cathedral The principal church of the diocese is the Cathedral of the Sacred Heart (; Asana Wihan Phra HaRueThai; location ) in Chiang Mai. The current church, already the third cathedral building of the diocese, was inaugurated on 30 October 1999. The first Sacred Heart church was built in 1931.