What is the name of a poem with less metrical restrictions before the Tang Dynasty?

It is called ancient poetry, also called ancient poetry and ancient style. Classical poetry, a genre of China's ancient poetry, refers to a poetic genre that was produced before the Tang Dynasty, which is opposite to the modern poetry (also known as modern poetry) that appeared in the Tang Dynasty. Its characteristic is that the metrical restrictions are not too strict.

Ancient poetry (ancient poetry) has a fixed poem and style. Compared with modern poetry, the metrical restrictions of ancient poetry are less. The length can be long or short, and the rhyme is more free and flexible. There are four words, five words, seven words, miscellaneous words and other forms. The ancient poems after the Han and Wei Dynasties are generally dominated by five or seven words, with certain rhyme and inflections.

All ancient poems are classified according to the number of words in the poem. Four-character ancient poems are referred to as four-character ancient poems for short; Five-character ancient poems are referred to as five-character ancient poems for short; Seven-character ancient poems are referred to as seven-character ancient poems for short. Four-character poems were adopted by people as early as the Book of Songs. But it gradually declined in the Tang Dynasty, and few people wrote it.

Extended data:

The difference between ancient poetry and modern poetry;

1, Metric: Classical poetry has no metrical requirements except rhyme; Modern poetry not only rhymes, but also needs to follow the meter;

2, the number of words: ancient poetry has four words, five words, seven words and miscellaneous poems; Modern poetry has only five words and seven words;

3, the number of sentences: classical poetry is not limited, up to hundreds of sentences, modern poetry quatrains, eight metrical poems, more than eight metrical poems;

4. Rhyme: Classical poetry uses rhyme freely, without too many restrictions, while modern poetry has strict requirements on rhyme parts and feet.

Reference source: Baidu Encyclopedia-Ancient Poetry