- Isnawī, ʻAbd al-Raḥīm ibn al-Ḥasan, 1305-1370. Sharḥ al-Minhāj2
- Israel2
- Israel--Acre2
- Italy--Ancona (Province)2
- Italy--Bergamo2
- Italy--Genoa2
- Italy--Lucca2
- Italy--Nizza Monferrato2
- Italy--Rivarolo Ligure2
- Italy--Rovigo2
- Italy--Senigallia2
- Italy--Syracuse2
- Italy--Volterra2
- Iṣfahānī, Maḥmūd ibn ʻAbd al-Raḥmān, 1275 or 1276-1348 or 1349. Tasdīd al-qawāʼid fī sharḥ Tajrīd al-ʻaqāʼid2
- Jainism2
- Jawī Zādah, Muḥammad ibn Ilyās, -1547 or 1548. Risālah fī al-masḥ ʻalá al-khuffayn2
- Jaʻbarī, Arslān ibn Yaʻqūb, -1300. Risālat al-tawḥīd2
- Jaʻbarī, Ṣāliḥ ibn Thāmir, d. 1306. Naẓm al-laʼālī2
- Jewish astrology2
- Jewish drama2