Punjabi is the official language of Punjab, and according to the 2001 Indian census, there are 29,102,477 speakers of the language in the country. The language is written in the Gurmukhi script (literally meaning ‘from the mouth of the Guru’) created by the Sikh Guru, Angad. The Sikh community revere a holy scripture called the Guru Granth Sahib, which is a compilation of Punjabi spiritual poetry of Guru Nanak, other Sikh Gurus as well as poets from other religions and communities. Sufi poetry in Punjabi is simple, with everyday concepts used to symbolise the relationship between man and god. The notable poets were Sheikh Farid, Shah Hussain and Bulle Shah. Kissa is a form of ballad based on tragic folklore with rich details of Punjabi life, social mores and culture and the most famous ones are Heer Ranjha by Waris Shah, Yusuf Zuleikha by Hafiz Barkhudar and Kissa Puran Bhagat by Kadir Yaar. Among modern Punjabi writers and poets, Bhai Vir Singh, Mohan Singh, Amrita Pritam, Gurdial Singh and Kartar Singh Duggal are some of the most respected names. A large part of modern Punjabi literature is centered around the Partition of India and Pakistan.