In the early period of Hindu-Muslim contact, there were close lingustic communications. The interactions between them deepened after the 12th century. In the 16th century, extensive Persian translations of the Sanskrit classics were done. Indo-Muslim writers left many works about Indian religious cults, custom and scientific thoughts. Among these works, we can find many technical terms and proper names of Indic origin transliterated in Perso-Arabic script. These are not only from Sanskrit but from other vernaculars as well. These vernaculars were not only introduced as foreign words but used as a means of communications. Perso-Arabic script was employed for poetry, prose and official orders in various regional languages. Besides Persian, the official language, Indic vernaculars played an important role in Hindu-Muslim communications.
Al-Bīrūnī pointed out the difficulties in pronunciation and transliteration of Indic words in the Perso-Arabic writing system. Indo-Muslim writers tried to overcome the inadequacy of their script for Indic languages. In the history of Arabic grammar, they established their own method to show the pronunciation of foreign words. This system called i'rāb has been inherited by many Islamic scholars and lexicographers. Abū'l Faẓl adopted the orthodox style, but Mīrzā Khān invented an original style of description. These transliterations and i'rāb give us much linguistic information about the languages of the day.
For example, Abū'l Faẓl's transliteration and i'rāb in the Ā'īn-i-Akbarī give us some materials for the linguistic study of the vernaculars used in the Mughal court. It sometimes shows the phonetic characters such as double consonants preceding the semivowels and in certain cases, it retains a final vowel from Sanskrit. In this way, the study of the tansliteration and i'rāb by Indo-Muslim writers reveals the phonetic features of and gives evidences on the growth of vernaculars of the day.