Between the 10th and 12th centuries CE, the nomadic Khitan dominated a large swath of Mongolia and Manchuria and created the Liao Dynasty, a substantial rival to China's Song Dynasty. They spoke an Altaic language, likely under the Mongolic family of languages. To write down their language, the Khitan people employed two distinct scripts in parallel. The first one, simply called the "large script" by Chinese sources, came into use at approximately 920 CE. The second one, not surprisingly called the "small script", was reputedly created by the Khitan scholar Diela around 925 CE. For the most part, the two systems did not seem to share any signs in common at all. A significant number of large script signs are modified version of Chinese signs, whereas the small script signs are original creations although reputedly with inspiration from the Uighur alphabet.
The Small Script
The Khitan language belongs to the Altaic family of languages, which means that its words contain multiple syllables with abundant suffixes for word derivation and verbal conjugation. The Khitan small script reflects this characteristic. Despite using the appearance of Chinese characters as an inspiration, the small script contains a majority of signs that are phonetic, representing syllables and single sounds. Combination of these signs to write out words and sentences that can fairly accurately represent the nuissances of Khitan language.
The following is a mostly complete set of phonetic signs in the Khitan small script.
Logograms are also present in the small script, but to a much smaller extent. The following are some of the logograms.
Logograms can also serve as phonetic signs by only providing the phonetic values of their words. This process is called the rebus principle and is found throughout the world's writing systems. A classic example of the rebus principle in English is a drawing of a bee followed by the numeral 4 to represent the word "before". Similary, in Khitan we find the logogram for "five", tau, followed by the phonetic signs li and a to write the word for "hare", taulia.
Generally, words are written vertically from top to bottom. However, when a word requires multiple component signs, the signs are assembled horizontally into pairs. Pairs are stacked on top of each other, and any extra sign (when the number of signs that make up the word is odd) is positioned at the center of the bottom. In the case of taulia, the signs for tau and li are side-by-side and a on centered below them.
Of interest is some of the signs that are not combined in pairs. These signs are logogram, and often are Chinese loanwords such as huang-tai-hou, each sign of which respectively has a corresponding Chinese character 王 "royal", 太 "great", 后 "queen". In essence, these are treated as three separate words, hence they are not put into a cluster.
The Large Script
The Khitan also employed another script traditionally called the large script. Unlike the small script, a good number of large script signs appear to have been borrowed directly or with some modification from Chinese characters. However, there are still others cannot be shown to have links with any Chinese characters, and thus probably were indigenous inventions.
Signs in the large script are written vertically starting from the top, with equal spacing between the signs. At first glance, the inventory of signs appears to be comprised mostly of logograms, which are signs that express morphemes or words. However, these signs are also used phonetically without any change to represent another word with the same sound. For example, the words "year" and "father" are both pronounced in Khitan as ai, and they are represented by the same sign.
Similarly, "winter" and "marry" are both u'ul in Khitan and represented by the same sign, which is clearly identical to the Chinese character for "winter", 冬. This illustrates how the borrowing process works. When a Chinese character is borrowed into Khitan large script, the original meaning is kept, but with Khitan pronuncation. Hence Chinese 冬 came to represent the sound u'ul, and therefore can be used to represent any other words or parts of words with this sequence of sounds.
Large script signs are also combined phonetically to write out words don't have a corresponding logogram. For example, much reminiscent of the small script, the word for "hare" taulia is written using the logogram for "five" tau and a sign for lia (which might actually be two signs joined together).
Other sign combinations are suffixes for word derivation. The word "country" is gur, but to derive the posessive form "of the country" the suffixed -en is added. Therefore there is a corresponding sign for this suffix. Also, gender marking in verbal conjugation is also marked. The logogram BORN (phonetical value unknown) can take on either a suffix of -en for males and -er for females.
Decipherments of both systems are still highly incomplete, although the Khitan small script is a better understood writing system due to a larger surviving corpus of text. Surviving texts of both scripts are inscriptions on monuments or tombs, sometimes accompanied by Chinese texts. Although the Chinese texts are not translations of the Khitan texts, enough parallels exist between the two that some decipherment has been successful.
The Khitan scripts were used only for roughly 200 years. The Khitan kingdom was brought to an abrupt end in 1125 CE when it was defeated by a former vassal and rising nomadic nation called the Jurchen, which would later become the Manchu. The Khitan people were absorbed and assimilated by the Jurchen. However, the Khitan also influenced Jurchen culture. The large script might have been an inspiration for the Jurchen script and some large script signs were likely borrowed into Jurchen, and also Jurchen used the both scripts in court along side Jurchen and Chinese scripts as official languages. It was only in 1191 CE by imperial decree that the Khitan scripts were suppressed, and the last vestiges of the Khitan culture disappeared from history.