This paper examines movement of texts and mathematical ideas between India, the Arabic-speaking Mediterranean world, the Byzantine Empire, and medieval/early modern Europe. It aims to unveil East-West networks of knowledge and break new ground in elucidating the way South Asia has shaped one of the most fascinating episodes in history. The transmission of the Indo-Arabic numerals from medieval India to the West via Arabic sources in the 12th‒14th centuries represents, in fact, a truly global paradigm shift. This paper focuses on languages and numerals, and provides a comparative analysis of mathematical manuscripts written in variety of languages ‒ including Sanskrit, Greek, Arabic, Latin, and early Italo-Romance dialects ‒ which cover a period of approximately 700 years (800 CE‒1500 CE). I demonstrate processes of knowledge transfer and that texts moved in a fluid environment where linguistic boundaries could be easily crossed.