The Swedish Viking Age lasted roughly from the 8th century to the 11th century. It is believed that Swedish Vikings and Gutar mainly travelled east and south, going to Finland, the Baltic countries, Russia, Belarus, Ukraine, the Black Sea and even as far as Baghdad. Their routes passed through the Dnieper south to Constantinople, on which they carried out numerous raids. The Byzantine Emperor Theophilos noticed their great skills in war, and invited them to serve as his personal bodyguard, known as the Varangian Guard. The Swedish Vikings, called Rus are believed to be the founding fathers of Kievan Rus'. The Arab traveller Ibn Fadlan described these Vikings as follows:The actions of these Swedish Vikings are commemorated on many runestones in Sweden, such as the Greece runestones and the Varangian runestones. There was also considerable participation in expeditions westwards, which are commemorated on stones such as the England runestones. The last major Swedish Viking expedition appears to have been the ill-fated expedition of Ingvar the Far-Travelled to Serkland, the region south-east of the Caspian Sea. Its members are commemorated on the Ingvar runestones, none of which mentions any survivor. What happened to the crew is unknown, but it is believed that they died of sickness.