Many non-Han (not culturally Chinese) ethnic groups in southwest China employ writing systems that were Chinese-based or Chinese-influenced. Collectively they are called "Siniform" scripts because they resemble Chinese in shape.

One of these Siniform scripts is the Yi script, employed to write the Yi or Lolo language (which belongs to the Tibeto-Burman language family). The Yi script is also known as Cuan, or Wei. The earliest surviving record of Yi dates from about 500 years ago. However, unlike other Siniform scripts, the form of its signs show a more indigenous development. Probably the form of its characters were not taken from Chinese, but instead appeared via stimulus diffusion from Chinese.

There are roughly eight to ten thousand Yi signs. Because there is a modern Yi script introduced in 1970, the old Yi writing system is named "Classic Yi". Like Chinese, Classic Yi is also logographic, that is, a sign stands for a whole morpheme. Many signs are "simple", meaning that they cannot be broken down or be derived from other signs. These include characters for 'sky', 'earth', 'snake', 'hand', etc.

Also, it is possible to derive a new sign from an old one by adding strokes to it, such as adding a loop to the sign for 'water' to make the sign for '(noise of) flowing water'. Another way of sign-formation involves duplicating a sign, such as the character meaning 'to hold (with both hands)' from the sign for 'hand'. Finally, two different signs can come together to form a single sign, such as combining 'half' and 'earth' to make 'accompany'.

Like archaic Chinese, homophonous (same-sounding) words in Yi can also be represented by the same sign. For example, in the picture below, the sign for 'snake' is also used to represent 'gold', 'yellow', and 'hereditary (son)'.

After 1970, a popular proposal introduced a "simplified" form of the Yi script. Taking 819 characters from the Classic script, "Modern Yi" is simply a syllabary. The Yi language is monosyllabic in the form of (Consonant Cluster)-Vowel. However, it allows 43 different consonant clusters to occur before the vowel. In addition, Yi is a tonal language, with 5 contrastive tones. The little double-digit numbers that you see after the phonetic transcription of a Yi sign designates its tone, where 5 is highest and 1 is lowest. Only 3 tones is indicated in the syllabary, (55), (33), and (21). The tone (34) is represented by the same sign for (33) plus an arch above it. Yi Script