Four tones (Middle Chinese)

They correspond to the phonology of Middle Chinese, and are named even or level (平 píng), rising (上 shǎng), departing or going (去 qù), and entering or checked (入 rù).

[2] (The last three are collectively referred to as oblique 仄 (zè), an important concept in poetic tone patterns.)

Indeed, implicit in the organisation of the classical rime tables is a different, but structurally equally valid, phonemic analysis, which takes all four tones as phonemic and demotes the difference between stop finals [p t k] and nasal finals [m n ŋ] to allophonic, with stops occurring in entering syllables and nasals elsewhere.

Some contemporary fāngyán such as Taiwanese Hokkien, Jin and Penang are said to preserve the entering tone, which is used as a marker to differentiate them from other varieties and also genetically classify them via the comparative method.

The four Early Middle Chinese (EMC) tones are nearly always presented in the order level (平 píng), rising (上 shǎng), departing (去 qù), entering (入 rù), and correspondingly numbered 1 2 3 4 in modern discussions.

In Late Middle Chinese (LMC), each of the EMC tone classes split in two, depending on the nature of the initial consonant of the syllable in question.

Discussions of LMC and the various modern varieties will often number these split tone classes from 1 through 8, keeping the same ordering as before.

These diacritics are also sometimes used when the phonetic realization is unknown, as in the reconstructions of Middle Chinese at the beginning of this section.

Some dialects have a complex tone splittings, and the terms dark and light are insufficient to cover the possibilities.

[8] This evolution of final glottal stop into a rising tone is similar to what happened in Vietnamese, another tonal language.

Support for this theory is found when examining Chinese loans into neighbouring East Asian languages.

Finally, the 平, or level tone, arose from the lack of sound at the ends of words, where there was neither [-s], a glottal stop, nor [-p], [-t], or [-k].

An old illustration of the four tone classes, in their traditional representation on a hand. In modern use, the diacritics all face the character, as in the table above.