During the Sui Dynasty, the first rhyme book appeared in the history of our country, which unified the rhyme rules of the whole country. This is the later "Ping Yun Shui". After the Tang Dynasty, all poems were written according to the flat rhyme standard.
Thirteen Rhymes is a new rhyme book based on the Central Plains Rhyme, which was produced in response to the needs of Yuan Dynasty zaju. Compared with Pingshui Rhyme, it disperses the original pentatonic rhyme into four other parts (Yin Ping, Yangping and Shangqu), making the original pentatonic rhyme become a tetratonic rhyme.
However, in the creation of metrical poems, people still generally use Pingshui rhyme, while Thirteen Rhymes are only used in the creation of Yuanqu and northern operas.
Since the May 4th Movement, I have been advocating writing new-style poems, but the rhyme has changed again. Nowadays, people generally rhyme with vowels of Chinese Pinyin based on the pronunciation of Putonghua, which is called new rhyme. However, in the creation of metrical poems, a large number of people still adhere to the standard of horizontal rhyme.
In the past, when rhyming according to the standard of rhyming books, the words in the same rhyme department rhymed, and the words in different rhymes could not be read together (except rhyming), and they were generally flat and even.
The rhyme of words is based on horizontal rhyme, which is summarized and merged, because the rhyme feet of words are flush;
Thirteen quotations are rhymes, and the rhymes of lyrics and songs are the same, even if the words are even. The only difference is the different rhyme. The most important thing is that words rhyme, not with other rhymes. Songs don't rhyme, so as long as they are in the same quotation, the words are even.
No matter Pingshui rhyme, Ci rhyme and Thirteen rhymes, their rhymes have nothing to do with today's Chinese phonetic vowels, so it is not appropriate to study them with Chinese phonetic alphabet.
In today's poetry creation, the vowels of Chinese Pinyin are generally used as the standard of rhyme, and the consistency of rhyme and tone is not considered in modern poetry. One advantage of using rhyme in Chinese Pinyin is that it is intuitive, so long as the vowels are consistent, they can be compared.
But there are also some special cases, such as i u v in a single vowel and e o in a two-letter vowel. A vowel has two vowels, as long as its belly and ending are the same, it can pass, such as an ian uan, a ua ia, ao iao, ou uo, i ei, etc. Er is generally only linked with I, but there are also different ones, such as ing, ong and eng. Some people agree that these three vowels can be linked, but others think that ing should be linked with ong and eng alone.