Bilingualism prior to Rosetta Stone (the software not the actual stone) and well-written language textbooks was typically the result of acquisition through immersion. Early interpreters were typically the result of immigration, family heritage, or trade. That being said, interpreters were a commodity to say the least, especially in the Americas. The most famous of these interpreters were Pocahontas and Sacagawea, two Native Americans who developed an understanding of English through their capture by Westerners. They then used this understanding to serve as interpreters for significant historical events, whether that be the establishing of peace between the English and the Powhatan or allowing the Lewis and Clark expedition to successfully navigate tumultuous relationships between Native Americans and Westerners.
These two interpreters are famous for their uniqueness and significance to the success of important historical events. That being said, on the other Eastern Hemisphere, there tends to be fewer stories of these singular and famous interpreters paving the way for historical successes. This is largely the result of pre-established trade routes, long-standing cultural connections, and immigration leading to a larger multilingual population between countries of significance and consequently the lack of a need for “celebrity” interpreters.
The early development of the Americas created the most significant language barrier of the last thousand years or so. Westerners came into contact with languages that they had never heard, with objects and items they had never seen, and with obscure intentions on both sides. The few bilingual persons used to negotiate treaties and deals that paved the way for the development of the Americas, acquired English unintentionally. These early interpreters were rather uncommon, especially with a level of fluency beyond those of the trappers and traders in the region, and had a paramount importance in the success of communicating between two societies that had no previous interactions.