The man who took these pictures was an early innovator in color photography and patronized by the Tsar, so he had a lot of opportunity. Some very gorgeous work, I love it.
Well, you still had to pay for all of this. It was just additionally limited how much you could purchase - with what is shown here being, then, the 'maximum'.
Mixture of places. Most I get from Rarehistoricalphotos. Many I get from Wikimedia commons. Some I google, when I have a piece of historical trivia I know but no picture to go with it. When I feel adventurous, I search online national archives, found some good Ethiopian pics in the Polish archives a while back.