Giuliano Castagna is a linguist specialised in the Modern South Arabian languages (MSAL). The MSAL are a subgroup of the Semitic language family and are known as: Mehri, Shahri (also known as Jibbali), Socotri, Bathari, Harsusi and Hobyot. They are spoken in Yemen and Oman, and their use has been declining in the last decades, so that all of them are now endangered. He is interested in the description of their grammar (especially the non-concatenative aspect of their nominal/adjectival morphology) and lexicon (with an emphasis on Shahri), the epigraphy of the areas where they are spoken, and their historical contact with the languages of the peoples involved in the pre-modern phase of the Indian ocean trade. Additionally, he has an interest in minority varieties of Arabic (that is, those spoken in countries whose official language is not Arabic), and in the methodologies of field linguistics.