An attempt to determine the number of languages in the world is affected by other factors. A few new languages do continue to be discovered, even these days, as unexplored regions of the world begin to be opened up. The discovery does not usually take place straight away. Often there are similarities with an already known language which make the investigators assume that what they have found is just a dialect of that language. Only after a considerable period of contact does it transpire that the speech is so different that it has to be considered a different language. It takes a language survey to establish the facts, and there are still many countries where such surveys are incomplete or have not even begun. The people may be known, but the identity of their language may not be. Because many such peoples are bilingual or multilingual, and converse with outsiders in lingua franca, it may take a while before linguists come to realize that there is an ethnic language there at all.