This book explores a pivotal period in the history of the book in the Islamic world and Iran, i.e. the Mongol period viewed in a long-term perspective, under the Ilkhanid and the Djalayirid dynasties. This book explores a pivotal period in the history of the book in the Islamic world and Iran, i.e. the Mongol period viewed in a long-term perspective, under the Ilkhanid and the Djalayirid dynasties. It examines the issue of the maturation of classical Arabic calligraphy through the life and work of Yāqūt al-Mustaʿṣimī, which are for the first time subjected to a systematic analysis, highlighting the importance of his school and the Baghdadi masters for the arts of the book of the following decades. The study also looks at the manuscripts of the Muslim Ilkhans and the Vizier Rashīd al-Dīn in the context of the birth of the kitābkhānah and the rise in the status of calligraphers and painters under the last Ilkhanids and the Djalayirids.