Island of the Jewel

The Island of the Jewel (Arabic: Jazīrat al-Jawhar‎‎) or Island of Sapphires (Arabic: Jazīrat al-Yāqūt‎‎) was a semi-legendary island in medieval Arabic cartography, said to lie in the Sea of Darkness near the equator, forming the eastern limit of the inhabited world.

The island does not appear in any surviving manuscript of Ptolemy's Geography nor other Greek geographers. Instead, it is first attested in the Ptolemaic-influenced Book of the Description of the Earth compiled by al-Khwārizmī around 833. Ptolemy's map ended at 180° E. of the Fortunate Isles without being able to explain what might lay on the imagined eastern shore of the Indian Ocean or beyond the lands of Sinae and Serica in Asia. Roman missions subsequently reached the Han court via Longbian (Hanoi) and Chinese Muslims traditionally credit the founding of their community to the Companion Saʿd ibn Abi Waqqas as early as the 7th century. Muslim merchants such as Soleiman established sizable expatriate communities; a large-scale massacre is recorded at Yangzhou in 760 amid the An Shi Rebellion against the Tang. These connections showed al-Khwārizmī and other Islamic geographers that the Indian Ocean was not closed as Hipparchus and Ptolemy had held but opened either narrowly or broadly.

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