India, June 21 -- This book is about the five partitions of the Indian Empire, which stretched from Aden in the west to Burma in the east to now 12 nations in three geographic regions. At the time, you write, even Britain downplayed its size. Nepal and Oman were never officially recognized. Arab states bordering the Ottoman Empire and Himalayan states near Tibet were left off the maps. But these were all run by the Indian political service, defended by the Indian army, their currency was the Indian rupee. So how did the British manage to hide them? And what did the Indian Empire actually look like?

So, for example, a 1909 map [Political Divisions of the Indian Empire by The Indian Gazetteer] shows Burma as British India, and Nepal and Bh...