Like all pre-Islamic scripts of Southeast Asia, the Batak script is also derived from the Brahmi script family. The Brahmi script was used more than 2000 years ago in India, and since then it has proliferated so that there are now dozens of writing systems that are derived from the Brahmi script. Some well-known Brahmi-derived scripts include Devanagai which is used to write Hindi and Sanskrit, Khmer (Cambodian), Thai, Kawi (Old Javanese), Hanacaraka (Javanese and Balinese), and Bugis. The Philippine scripts such as Tagbanua, Hanunó’o or Buhid are also ultimately derived from the Brahmi script. Like the Batak script, the Philippine scripts are also called Surat, Sulat, or Suyat. Surat does not only mean ‘script’, but it also means letter—both in the meaning ‘a unit of an alphabet’ and ‘a written message conveyed from one person to another person’.
The scripts closest to the Batak letters are the Sumatran scripts such as the Surat Lampung Had, Surat Incung script (Kerinci), and Surat Ulu (Rejang, Lebong, Bengkulu).
All of these writing systems have several characteristics in common:
Although the Toba Batak script is referred to as the surat na sampulu sia (the 19 characters), there are actually only 18 characters. The 19th character is the letter nya that is only needed to write the Mandailing language – the Toba Batak sound system does not include the [ɲ] sound (ny). This also shows that the Batak script developed earlier in Mandailing. If in a pustaha (bark book) there is a text related to the Batak script, the character nya is always included in the alphabet.
The following is a list of characters for each regional language. It should be noted that there are four characters which may or may not be used. The characters are / i / and / u / (ᯤ and ᯥ) and / nda / and / mba / (ᯣ and ᯢ) which are only used in the Karo language (and there is no need to use any of those characters). Furthermore, in Toba Batak the letters /wa/ and /ya/ (ᯋ and ᯛ) are also optional.