The Anatolian peninsula, comprising most of modern Turkey, is one of the oldest permanently settled regions in the world. Various ancient Anatolian populations have lived in Anatolia, from at least the Neolithic until the Hellenistic period. Many of these peoples spoke the Anatolian languages, a branch of the larger Indo-European language family: and, given the antiquity of the Indo-European Hittite and Luwian languages, some scholars have proposed Anatolia as the hypothetical centre from which the Indo-European languages radiated. The European part of Turkey, called Eastern Thrace, has also been inhabited since at least forty thousand years ago, and is known to have been in the Neolithic era by about 6000 BC.