The Evolution of Consonant Clusters in Vietnamese: Reconstruction Based on Manuscripts in Quốc ngữ Script from 17th to 19th Centuries

In the Dictionarium Annamiticum Lusitanum et Latinum published by Alexandre de Rhodes in 1651, the graphemes bl-, ml-, tl-, pl-, mnh- of five initial clusters *ɓl-, *ml-, *tl-, *pl-, *mɲ- can be found. This dictionary often presents two graphemes for the same phoneme, thus indicating both its old and new forms. This article aims first to analyze the graphic variants appearing in the Dictionarium. While Đoàn (2008) focused on orthographic changes in 18th-century texts without addressing regional variation, Vũ (2019) explicitly noted that some consonant clusters evolved differently across regions, although without providing a precise chronology for these developments. Building on this previous work, this study seeks to trace the evolution of three clusters across different periods and regions—Tonkin, Upper Cochinchina (present-day Central Vietnam), and Lower Cochinchina—based on an analysis of around one hundred letters and reports written by priests in Tonkin and Cochinchina from the 17th to the 19th century. The results of this study show that in Tonkin, the *tl- group disappeared in the 17th century and the other two groups *ml-, *tl- in the 19th century. Whereas in Cochinchina (central and southern Vietnam today), the two groups *ɓl- and *ml- disappeared first, the group *tl remained there longer.