Colin McEvedy: The four volume Penguin Atlas series, and particularly the Atlas of Ancient History, was probably the true inspiration of the project, when I first saw it in the 1970’s.
Frank Reed author of Centennia HistoricalAtlas.com: The CENTENNIA Historical Atlas, Europe and the Middle East, 1000AD to the Present: Still the masterwork for this genre of software.
Trevor Bryce: The indefatigable author of The Routledge Handbook of The Peoples and Places of Ancient Western Asia, a wonderful, encyclopedic index.
Ian Mladjov: author of s series of maps Ian Mladjov's Resources - Maps (google.com) ; much appreciated for his satrapy maps of the Achaemenid Empire.
Thomas Lessman: Publisher of a terrific of series of maps, particularly of the Eastern Hemisphere World History Maps.
The Cambridge Ancient History series’ including volumes on China and India, are the major source for the events depicted.
The Barrington Atlas of the Ancient World: beautiful and comprehensive, especially when used in conjunction with pleiades.stoa.org. The Atlas is now hosted by the Ancient World Mapping Center (unc.edu)
The World History Encyclopedia and their excellent interactive map at https://www.worldhistory.org/map/
Wiki: how did we ever live without this tool?
Omniatlas and Rick Westera: source of beautiful and wide-ranging maps which cover the world at https://omniatlas.com
Linn Atlas and their wonderfully detailed maps available on their Facebook site as well as on YouTube; I am particularly grateful for their cooperation in producing the latest version of the China maps.
And many, many more!