have happened in the 6th century, and been an expulsion of the immigrants from the Danube: "the only thing we can say with reasonable certainty is that a small group of Eruli lived there for some 38-40 years in the first half of the 6th century A.D.". He proposes that the evidence makes it most likely that "a loose group of Germanic warriors which came into being in the late 3rd century in the region north of the Danube limes that extends roughly from Passau to Vienna". On the Pontic-Caspian steppe The Heruli are believed to have migrated towards the region north of the Black Sea in the 3rd century AD. Other Germanic peoples, such as the Rugii and the Goths, are believed to have carried out a similar migration at this time. These peoples replaced the Sarmatians as the dominant power north of the Black Sea. The Sarmatians had in the 1st century AD replaced the Bastarnae, who are believed to have been a Germanic people. The arrival of the Heruli has been seen as part of a bigger cultural shift in this region, involving the migration from the northwest of Germanic peoples, who replaced the Sarmatians as the dominant power in the region. The first relatively clear mention of the Heruli by Graeco-Roman writers concerns two major campaigns into the Balkans of 267/268 and 269/270. Goths, Heruli (referred to as "Eluri", Ἔλουροι, in the oldest sources), and other "Scythian" peoples from the region of the Sea of Azov, took control of Black Sea Greek cities, and gained a fleet that they used to launch raids along the northern Black Sea and as far as Greece and Asia Minor. These invasions began in the reign of Gallienus (260-268 AD), and continued until at least 269 during the reign of Marcus Aurelius Claudius, who subsequently took up the title "Gothicus" due to his victory. In 267, Heruli (Αἴρουλοι) commanded a naval attack from the Sea of Azov, past the Danube delta, and into the straits of the Bosphorus (the area of modern Istanbul). They took control of Byzantion and Chrysopolis before retreating to the Black Sea. Emerging to raid Cyzicus, they subsequently entered the Aegean Sea, where they troubled Lemnos, Skyros and Imbros, before landing in the Peloponnese. There they plundered not only Sparta, the closest city to their landing site, but also Corinth, Argos, and the sanctuary of Zeus