Stories common to a particular culture, but not supported by external sources (such as the tales surrounding King Arthur) are usually classified as cultural heritage or legends, because they do not support the "disinterested investigation" required of the discipline of history.[10][11] Herodotus, a 5th-century BC Greek historian is considered within the Western tradition to be the "father of history", and, along with his contemporary Thucydides, helped form the foundations for the modern study of human history. Their work continues to be read today and the divide between the culture-focused Herodotus and the military-focused Thucydides remains a point of contention or approach in modern historical writing. In the Eastern tradition, a state chronicle the Spring and Autumn Annals was known to be compiled from as early as 722 BC although only 2nd century BC texts survived.