Answer:
Isolated languages persisted over time because of a lack of outside influence.
Step-by-step explanation:
There are tens of thousands of languages around the world, divided into numerous language families, and all of them are unique and beautiful in their own way. Not all languages managed to persist and survive till modern times though, and nowadays we are witnessing that more and more are on the verge of disappearing. The main reason for the disappearance of languages has been the outside influence of other cultures and languages.
Contrary to that, there are languages that even though are not so widespread, have managed to persist for thousands of years. This has been possible because of a lack of contact with people that spoke other languages and lack of outside influence. Most notably, such languages can be found in the central part of Africa, Australia, New Zealand, and the rest of Oceania, Siberia, as well as the Amazon and the rainforests of Southeast Asia.