From Alamut to Lisbon, Portugal
Vasco de Gama the Portuguese voyager owes his success to the Imams in Alamut.
JUVEINI was the Vazir( Vizier) of Halagu Khan.
Juveini asked permission of Halagu Khan, to visit the library, before he destroyed and burnt it.
Juveini, destroyed the copies of Quran and “choice” books.
However, Juveini picked out astronomical instruments, armillary spheres, COMPLETE AND PARTIAL ASTROLABS and other instruments from the Library before burning it.
A lot of religious literature had escaped from Egypt and Alamut and was in custody of Ismaili communities and was preserved, including the SCIENTIFIC LEGACY.
Nasir al din Tusi (1247 d) who had until then served the Ismailis of Alamut, was one of the most famous astronomers and mathematicians of his period; was ordered by the Mongol King Halagu to develop the most modern observatory, which he developed and built in Maragha, in the Northwestern Iranian province of Azerbaijan.
Astronomers from China, Iran, Syria and Iraq worked at this institute and produced new astronomical tables called ZIJ ILKHANID TABLES, (the prince of the land tables, which name, the Mongols were using), al- Zij- al – il-khani.
These tables were brought to Muslim Andalusia via Salamanca and Zaragoza by a Jewish Professor, Rabbi ben Samuel Zacuto.
When the Jews were expelled from Spain, Zacuto fled to Lisbon Portugal to the court of King John II of Portugal.
It was Zacuto’s new tables that guided Portuguese navigators, on their voyages around West Coast of Africa.
It was Zacuto who made the ASTROLAB FOR VASCO DE GAMA, which Vasco de Gama carried with him on his flagship voyage around the Cape of Good Hope, to India in 1497-98.
Conclusion : It was the knowledge of Dai Nasir al din al Tusi, working under the Imam of the Time of Alamut, Rukn Al Din Khurshah, (and later on forced to work for Mongol King Halagu) who was eventually responsible for the success of Vasco De Gama.
Bibliography: The Fatimids and their Traditions of Learning : Heinz Halm