Lepcha

Lepcha (also known as Rong or Rong-Ring) is a Unicode block containing characters for writing the Lepcha language of Sikkim and West Bengal, India.

The specific feature of this alphabet is that it's an abugida (consonant alphabet, where the vowels depend a lot on the consonants). However, it's a bit unusual for abugidas that the syllabic endings of the words in Lepcha are written with the Diacritical marks.

The Lepcha script comes from the Tibetan script, possibly with some influence from the Burmese script. The tradition suggests that the script was devised at the beginning of the 18th century by prince Chakdor Namgyal of the Namgyal dynasty of Sikkim, or by scholar Thikúng Men Salóng in the 17th century. The early Lecha manuscripts were written vertically, apparently, under Chinese influence. However, later they switched to horizontal writing, but the letters kept their orientation, rotated 90 degrees from their Tibetan prototypes. This was reflected in the unusual way of writing final consonants. As for the rotation, it must have happened in the XVIII century.

The Lepcha script used to be in action long before now, and a lot of books were published in this writing. At the end of XIX and the beginning of XX centuries it was really blooming, but for a short period of time. It is believed that nowadays it's no longer in use.