The Soyombo script (Mongolian Соёмбо бичиг, soyombo bichig) is an abugida developed by the Mongolian monk and scholar Bogdo Zanabazar in 1686 to write Mongolian. It can also be used to write Tibetan and Sanskrit.
A special character of the script, the Soyombo symbol, became a national symbol of Mongolia, and has appeared on the national flag since 1921, and on the national coat of arms since 1992, as well as money, stamps, etc.
The Soyombo script was created as the fourth Mongolian script, only 38 years after the invention of the Clear script.
A legend talks about Zanabazar seeing letter-like signs in the sky one night, which he turned into his new script. The name of the script alludes to this story. It is derived from the Sanskrit word Svayambhu, meaning "created out of itself".
The syllabic system in fact appears to be based on Devanagari script, while the base shape of the letters is derived from the Nepalese Lantsa script (rajana). Details of individual characters resemble traditional Mongolian script and the Orkhon script. It is unclear whether Zanabazar designed the Soyombo symbol himself, or if it had existed beforehand.
The eastern Mongols used the script primarily as a ceremonial and decorative script. Zanabazar had created it for the translation of Buddhist texts from Sanskrit or Tibetan, and both he and his students used it extensively for that purpose.
As it was much too complicated to be adopted as an everyday script, its use is practically nonexistent today. Aside from historical texts, it can usually be found in temple inscriptions. It also has some relevance to linguistic research, because it reflects certain developments in the Mongolian language, such as that of long vowels