What was sherlock holmes able to deduce ?

sherlock holmes uses inductive reasoning not deductive reasoning.

Deductive reasoning starts with a hypothesis and then examines facts  then reaches a logical conclusion.

Explanation:

indigenous people north and south were displaced, died of disease, and were killed by europeans through slavery, rxpe, and war. in 1491, about 145 million people lived in the western hemisphere. by 1691, the population of indigenous americans had declined by 90-95 percent, or by around 130 million people."