The Kosovo Myth (Косовски мит / Kosovski mit), also known as the Kosovo Cult (Косовски култ / Kosovski kult) and the Kosovo Legend (Косовска легенда / Kosovska legenda), is a Serbian national myth based on legends about events related to the Battle of Kosovo (1389). It has been a subject in Serbian folklore and literary tradition and has been cultivated oral epic poetry and guslar poems. The final form of the legend was not created immediately after the battle but evolved from different originators into various versions. In its modern form it emerged in 19th-century Serbia and served as an important constitutive element of the national identity of modern Serbia and its politics. The Serbian ruler Lazar was challenged by the Ottoman Sultan Murad I to the battle at the Kosovo Polje. According to the Myth, Lazar chose to die as a martyr, with the aim of providing Serbs with a place in the Kingdom of Heaven, instead of the "earthly kingdom" and victory in the battle. In the myth, as opposed to what actually happened in reality, Vuk Branković withdrew his troops at crucial moments, thus becoming a symbol of a betrayal, while Miloš Obilić assassinated the Sultan Murad I and then was executed. In fact, Branković fought valiantly to the end. In Ottoman Serbia, the myth was interpreted as a fatalistic ideological acceptance of the Ottoman Empire and originally was not linked to the Serbs as a people, but to the downfall of Serbian feudal society. In the modern narratives of the myth, defeat in battle was characterized as the downfall of the glorious medieval Serbian state and subsequent a long-lasting Ottoman occupation and slavery. According to legend the sacrifice of Lazar and his knights resulted in the defeat, while the Serbs were presented as the chosen people who signed a Covenant with God. The Kosovo Myth is modeled on well-known Christian symbols, such as the biblical Last Supper, Judas' betrayal and numbers that have religious associations. It pictures Serbia as essentially a variant of the Antemurale Christianitatis motif (bulwark of Christianity) against the Ottoman Empire.