I've mentioned a few times how much I like Peter Hopkirk's books, which are mostly histories of Central Asia/India during the Great Game period. Part of this is just that I'm kind of a fan of that period (including mysteries set in that period), but I also think they are easy to read and really bring the history to life. Now a bunch of them have dropped in price, mostly at Kindle UK, including:
Trespassers on the Roof of the World: The Race for Lhasa, £0.99
Kindle UK:
https://www.amazon.co.uk/dp/B0074OKE38
Kindle UK/Smile:
https://smile.amazon.co.uk/dp/B0074OKE38
Foreign Devils on the Silk Road: The Search for the Lost Treasures of Central Asia, £1.99
Kindle UK:
https://www.amazon.co.uk/dp/B005HWB2QW
Kindle UK/Smile:
https://smile.amazon.co.uk/dp/B005HWB2QW
On Secret Service East of Constantinople: The Plot to Bring Down the British Empire, £2.99
Kindle UK:
https://www.amazon.co.uk/dp/B005HVR9WY
Kindle UK/Smile:
https://smile.amazon.co.uk/dp/B005HVR9WY
Setting the East Ablaze: Lenin's Dream of an Empire in Asia, £3.99 (not really dropped in price, but still inexpensive), also $3.99 in the US
Kindle UK:
https://www.amazon.co.uk/dp/B0071MDD6I
Kindle UK/Smile:
https://smile.amazon.co.uk/dp/B0071MDD6I
Kindle US:
https://www.amazon.com/dp/B00GVFNN1Q
Kindle US/Smile:
https://smile.amazon.com/dp/B00GVFNN1Q
The Great Game: On Secret Service in High Asia, £4.99
Kindle UK:
https://www.amazon.co.uk/dp/B003Y3BLNK
Kindle UK/Smile:
https://smile.amazon.co.uk/dp/B003Y3BLNK
And finally,
The Quest for Kim, which is not quite a history, but not really fiction either - it documents Hopkirk's attempts, some successful and some not, to trace the paths of Kipling's Kim in modern day South Asia, £1.99/$1.99
Kindle UK:
https://www.amazon.co.uk/dp/B00713DMTU
Kindle UK/Smile:
https://smile.amazon.co.uk/dp/B00713DMTU
Kindle US:
https://www.amazon.com/dp/B00GW4L0HK
Kindle US/Smile:
https://smile.amazon.com/dp/B00GW4L0HK
I haven't been able to find most of Hopkirk's books in the US as of now, which is odd because I bought almost all of them a few years ago at Kobo and Kindle US. Perhaps some publisher issue...