How did Sacagawea and the native Americans tribes contribute to the success of the expedition?

Sacagawea also made a miraculous discovery of her own during the trip west. When the corps encountered a group of Shoshone Indians, she soon realized that its leader was actually her brother Cameahwait. It was through her that the expedition was able to buy horses from the Shoshone to cross the Rocky Mountains.

Explanation:

in his book, the riddle of the rosetta stone, james giblin talks about how there was a young british polymath and physician named thomas young who made a lot of advances on the deciphering of the rosetta stone. he says that even though young made a lot of mistakes because he was working under false assumptions, he also made huge contributions like deciphering three out of the seven symbols (more than anyone else before him). young published his findings and continued his good work but he wasn't able to progress much further due to some unfavorable situations, he still laid the basis for many other scholars and of course for the man who has been generally known to have deciphered it, jean-françois champollion