 He spent the last 30 years of his life traveling to the remote parts of Asia and Africa and writing about what he saw.One journey brought him 20° south of the equator along the East African coast where he discovered large populations in regions the ancient Greek writers had deemed, from logic rather than knowledge, were uninhabitable.Ibn Hawqal based his great work of geography on a revision and augmentation of the text called "Masālik ul-Mamālik" by Istakhri (951 AD), which itself was a revised edition of the "Ṣuwar al-aqālīm" by Ahmed ibn Sahl al-Balkhi, (ca.