The establishment of the Preslav and Ohrid literary schools in the 10th century is associated with a golden period in Bulgarian literature during the Middle Ages. The schools' emphasis on Christian scriptures made the Bulgarian Empire a centre of Slavic culture, bringing Slavs under the influence of Christianity and providing them with a written language. Its alphabet, Cyrillic script, was developed by the Preslav Literary School. The Tarnovo Literary School, on the other hand, is associated with a Silver age of literature defined by high-quality manuscripts on historical or mystical themes under the Asen and Shishman dynasties. Many literary and artistic masterpieces were destroyed by the Ottoman conquerors, and artistic activities did not re-emerge until the National Revival in the 19th century. The enormous body of work of Ivan Vazov (1850–1921) covered every genre and touched upon every facet of Bulgarian society, bridging pre-Liberation works with literature of the newly established state. Notable later works are "Bay Ganyo" by Aleko Konstantinov, the Nietzschean poetry of Pencho Slaveykov, the Symbolist poetry of Peyo Yavorov and Dimcho Debelyanov, the Marxist-inspired works of Geo Milev and Nikola Vaptsarov, and the Socialist realism novels of Dimitar Dimov and Dimitar Talev. Tzvetan Todorov is a notable contemporary author, while Bulgarian-born Elias Canetti was awarded the Nobel Prize in Literature in 1981.