 For several centuries there were separate Hittite groups, usually centered on various cities.But then strong rulers with their center in Hattusa (modern Boğazkale) succeeded in bringing these together and conquering large parts of central Anatolia to establish the Hittite kingdom.The early history of the Hittite kingdom is known through tablets that may first have been written in the 17th century BC, possibly in Hittite; but survived only as Akkadian copies made in the 14th and 13th centuries BC.