One such situation, rather rare today, involves contact between relatively small groups leading to extensive multilingualism and diffusion of both vocabulary and grammar across their languages. Examples include areas of Papua New Guinea, the Amazon basin, and the Australian desert. Other situations involve geographic proximity between different language communities with only slow spread of features across languages, creating so-called sprachbund or linguistic areas. An example is the Balkan sprachbund, where speakers of typologically distinct languages like Greek, Albanian, Romanian, Bulgarian, etc. have adopted features from each other over the centuries.