Neolithic remains from Knossos date back to about 6000 B.C. After the collapse of the Bronze Age Minoan civilization, during which Greek was introduced in the fifteenth century B.C. , the Dorian invasions—which appear not to have eradicated the preexisting local culture entirely—were followed by a cultural efflorescence that continued into Roman (from 67 B.C. ) and early Byzantine times. Muslim Saracen invaders, who came from Spain by way of Egypt in about A.D. 823, may have presided over the development of the Cretan dialects into roughly their present form. They were driven out by the Byzantine Emperor Nikiforos Fokas in 961. Alexios Comnenon I allegedly brought twelve noble families ( arkhondopouli ) from Byzantium to repopulate the ravaged island. Some of their names still survive, as do surnames of Venetian settlers who arrived after the collapse of the short-lived (1204-1210) Genoese occupation. The Venetian period was one of great cultural revival, with Italian-influenced literature and art incorporating local verse traditions and Byzantine iconography; after the collapse of most of the island in 1645-1646 and of Iraklio (Candia) in 1669, refugees carried this literary culture to the Ionian Islands. The Turkish period was marked by bloody revolts and fierce repression. In 1898 Crete, under the joint supervision of Britain, France, Italy, and Russia, became a semiautonomous protectorate, and in 1913 it was united with Greece. The 1941-1944 German occupation was extremely harsh and revived the traditional Cretan values of warlike independence. Despite the prominence of Cretan politicians in national life, Cretans have felt excluded from the centers of political power in the larger national entity. They have been strongly antimonarchist and prosocialist, the latter tendency being only slightly offset by powerful liberal and right-wing political patronage in the rural areas. Despite sporadic separatism in the past, Crete now appears solidly embedded in the national political structure, although cultural and political hostility to Athens persists. The more isolated mountain dwellers' tradition of especially active resistance to authority may account for some distinctive local cultural forms, some of which suggest links with much earlier periods.