I had my girlfriend look at the pictures of this saddle, and she is a saddlemaker by trade. Based on the pictures her response is:
Brown Dyed Black: Probably originally a black saddle; black saddles do turn brown over time, especially if they are out in the sun or due to wear.
Pin Type Stirrup adjustment: The pin stirrup adjustment is pretty standard. hard to date based on that feature
Age: Pretty sure it isn't from the 1800s. Saddles from that time period were not ornate, they were working saddles. Based on the tooling, conchos, metal work, and stirrups, it was probably a parade or show saddle. Difficult to guess age from photos.
Best advice, find a local saddlemaker or tack shop and show it to them. If you let me know where you are , maybe I can recommend someone in your area.
Hope that helps.
Hudsonhacker