Encyclopedia of Islam

The Encyclopedia of Islam, originally published in 1913—1938, details all known things about the Islamic world, including topics such as: distinguished Muslims of every age and land, tribes and dynasties, crafts and sciences, political and religious institutions, geography, ethnography, flora and fauna of the various countries and, the history, topography and monuments of the major towns and cities. 

Currently, there is a second edition (pictured) that was published in 1954—2008, which has a greater emphasis on economic and social topics. It is considered to be “the authoritative source not only for the religion, but also for the believers and the countries in which they live,” according to the Internet Archive. The Encyclopedia includes articles written by prominent scholars, along with maps, illustrations, and tables, and has been released in English, French, and German.

Information sources:
 https://web.archive.org/web/20160111023510/http://www.brill.com/publications/encyclopaedia-islam
https://web.archive.org/web/19990128144234/http://www.library.yale.edu/rsc/islam/dicts.htm
https://iranicaonline.org/articles/encyclopaedia-of-islam