The entire Guru Granth Sahib is written in the Gurmukhi script, which was standardized by Guru Angad Dev in the 16th century. According to Sikh tradition and the Mahman Prakash, an early Sikh manuscript, Guru Angad Dev had taught and spread the Gurmukhi script at the suggestion of Guru Nanak Dev which has invented the Gurmukhi script. The word Gurmukhī translates to "from the mouth of the guru ''. It descended from the Laṇḍā scripts and was used from the outset for compiling Sikh scriptures. The Sikhs assign a high degree of sanctity to the Gurmukhī script. It is the official script for writing Punjabi in the Indian State of Punjab.
when was the first guru granth sahib written
16th century