Zonal constructed languages are constructed languages made to facilitate communication between speakers of a certain group of closely related languages. They form a subgroup of the international auxiliary languages, but unlike languages like Esperanto and Volapük they are not intended to serve as languages for the whole world, but merely for a limited linguistic or geographic area. There is some overlap with the term "Euroclone", however, the latter usually refers to languages intended for global use but based (almost) exclusively on European material. Another related concept is known as a koiné language, a dialect which naturally emerges as a means of communication among speakers of divergent dialects of a language.