They are mainly known from the Royal Archives of the Hittite kingdom preserved at Boghazköy. Hittite is the best known and is represented by lengthy texts treating a wide variety of topics. The other languages are known from fragments. They are distinguished from Hittite and each other by the inclusion of different non Indo-European elements in their vocabularies.

Greek speakers encountered Lydian and Lycian on the coast of Asia Minor. Bilingual Greek-Lycian inscriptions are known. There is some slight evidence in Hittite official documents for contact between the Mycenean speakers from mainland Greece and Hittite. Official diplomatic correspondence in Hittite has been found in the Egyptian royal archives at Tel el Amara.