| Affricate | | | x () | | |- ! colspan="2" | Liquid | r | l | | | |} Old Vietnamese/Ancient Vietnamese was a Vietic language which was separated from Viet–Muong around 9th century, and evolved to Middle Vietnamese by 16th century. The sources for the reconstruction of Old Vietnamese are Nom texts, such as the 12th-century/1486 Buddhist scripture Phật thuyết Đại báo phụ mẫu ân trọng kinh ("Sūtra explained by the Buddha on the Great Repayment of the Heavy Debt to Parents"), old inscriptions, and late 13th-century (possibly 1293) Annan Jishi glossary by Chinese diplomat Chen Fu (c. 1259 – 1309). Old Vietnamese used Chinese characters phonetically where each word, monosyllabic in Modern Vietnamese, is written with two Chinese characters or in a composite character made of two different characters. It conveys the transformation of Vietnamese lexicons from sesquisyllabic to fully monosyllabic through monosyllabization process under pressures of Chinese linguistic influence, characterized by phenomena such as the reduction of minor syllables; loss of affixal morphology drifting towards analytical grammar; simplification of major syllable segments, and change of suprasegment instruments. For examples, the modern Vietnamese word "trời" (heaven) was read as *plời in Old/Ancient Vietnamese and as blời in Middle Vietnamese. Middle Vietnamese The writing system used for Vietnamese is based closely on the system developed by Alexandre de Rhodes for his 1651 Dictionarium Annamiticum Lusitanum et Latinum. It reflects the pronunciation of the Vietnamese of Hanoi at that time, a stage commonly termed Middle Vietnamese (). The pronunciation of the "rime" of the syllable, i.e. all parts other than the initial consonant (optional glide, vowel nucleus, tone and final consonant), appears nearly identical between Middle Vietnamese and modern Hanoi pronunciation. On the other hand, the Middle Vietnamese pronunciation of the initial consonant differs greatly from all modern dialects, and in fact is significantly closer to the modern Saigon dialect than the modern Hanoi dialect. The following diagram shows the orthography and pronunciation of Middle Vietnamese: {| class="wikitable" style=text-align:center |- ! colspan="2" | ! Labial ! Dental/Alveolar ! Retroflex ! Palatal ! Velar ! Glottal |- ! colspan="2" | Nasal | m | n | | nh | ng/ngh | |- ! rowspan="3" | Stop | style="background: #f2f2f2;" | tenuis | p | t | tr | ch | c/k | |- | style="background: #f2f2f2;" | aspirated | ph | th | | | kh | |-