Đàng Trong
By far the most widespread Christian denomination in Vietnam, Roman Catholicism first entered the country through Portuguese and Spanish missionaries in the 16th century, although these earliest missions did not bring very impressive results. Only after the arrival of Jesuits, who were mainly Italians, Portuguese, and Japanese, in the first decades of the 17th century did Christianity begin to establish its positions within the local populations in both domains of "Đàng Ngoài" (Tonkin) and "Đàng Trong" (Cochinchina). Two priests Francesco Buzomi and Diogo Carvalho established the first Catholic community in Hội An in 1615. Between 1627 and 1630, Avignonese Alexandre de Rhodes and Portuguese Pero Marques converted more than 6,000 people in Tonkin.