This work, published in Delhi in 1920, is a history of the Urdu language from its origins to the development of an Urdu literature. Urdu and Hindi share an Indo-Aryan base, but Urdu is associated with the Nastaliq script style of Persian calligraphy and reads right-to-left, whereas Hindi resembles Sanskrit and reads left-to-right. The earliest linguistic influences in the development of Urdu probably began with the Muslim conquest of Sindh in 711. The language started evolving from Farsi and Arabic contacts during the invasions of the Indian subcontinent by Persian and Turkic forces from the 11th century onward. Urdu developed more decisively during the Delhi Sultanate (1206–1526) and the Mughal Empire (1526–1858). When the Delhi Sultanate expanded south to the Deccan Plateau, the literary language was influenced by the languages spoken in the south, by Punjabi and Haryanvi, and by Sufi and court usage. The earliest verse dates to the 15th century, and the golden period of Urdu poetry was the 18th–19th centuries. Urdu religious prose goes back several centuries, while secular writing flourished from the 19th century onward. Modern Urdu is the national language of Pakistan and is also spoken by many millions of people in India.