The reason for one language to borrow word or words from another is simple: the source language might have words or phases, for which there are no equivalents in the other language. This can be words describing objects, events, social, political and cultural institutions or even abstract contacts that cannot be found in the culture of the “borrowing” language
Take for example English. Words such as tepee, wigwam or igloo are loanwords describing types of houses. Opera and ballet were borrowed to described cultural institution and perestroika, glasnost or apartheid were borrowed for describing cultural concepts.
In linguistics, it happens quite often that one culture borrows loanwords from another culture to describe cultural, social or technological innovations and advancements.