The principal subject of the "Gesta" is the Hungarian conquest of the Carpathian Basin at the turn of the 9th and 10th centuries, and it writes of the origin of the Hungarians, identifying the Hungarians' ancestors with the ancient Scythians. Many of its sources—including the Bible, Isidore of Seville's "Etymologiae", the 7th-century "Exordia Scythica", the late 9th-century Regino of Prüm's "Chronicon", and early medieval romances of Alexander the Great—have been identified by scholars. Anonymus also used folk songs and ballads when writing his work. He knew a version of the late 11th-century "Hungarian Chronicle" the text of which has partially been preserved in his work and in later chronicles, but his narration of the Hungarian Conquest differs from the version provided by the other chronicles. Anonymus did not mention the opponents of the conquering Hungarians known from sources written around 900, but he wrote of the Hungarians' fight against rulers unknown from other sources. According to a scholarly theory, he used place names when naming the opponents of the Hungarians.