Metre (poetry) of over some two-and-a-half millennia. Beginning with the earlier recorded forms: the Classic of Poetry tends toward couplets of four-character lines, grouped in rhymed quatrains; and, the Chuci follows this to some extent, but moves toward variations in line length. Han Dynasty poetry tended towards the variable line-length forms of the folk ballads and the Music Bureau yuefu. Jian'an poetry, Six Dynasties poetry, and Tang Dynasty poetry tend towards a poetic metre based on fixed-length lines of five, seven, (or, more rarely six) characters/verbal units tended to predominate, generally in couplet/quatrain-based forms, of various total verse lengths. The Song poetry
Poetry have challenged the traditional definitions of the sonnet form, rendering entire sequences of "sonnets" that often lack rhyme, a clear logical progression, or even a consistent count of fourteen lines. "Shi" () Is the main type of Classical Chinese poetry. Within this form of poetry the most important variations are "folk song" styled verse ("yuefu"), "old style" verse ("gushi"), "modern style" verse ("jintishi"). In all cases, rhyming is obligatory. The Yuefu is a folk ballad or a poem written in the folk ballad style, and the number of lines and the length of the lines could be irregular. For the