Historical event that sounds fake but is actually real; The Viking raid of Tabarstan on the Caspian coast of Iran
In 913, the viking made it as far as the Caspian coast of Iran. A massive fleet of approximately 500 Viking ships (roughly 15,000 to 20,000 men) navigated the Volga River from Eastern Europe, entered the Caspian Sea, and reached the northern Iranian shoresmen. The raiders pillaged the wealthy regions of Gorgan, Mazandaran, and Gilan, taking extensive plunder and capturing local inhabitants to be sold into slavery. The expedition ultimately ended in disaster. The fierce, warlike local tribes of the region (who had never been conquered by the Arabs) retaliated aggressively. Under the cover of night, the Gilanis and Deylamites set fire to the Viking fleet on the shores, effectively cutting off the raiders' escape routes and wiping out the majority of the surviving Norsemen.
Source: Gunilla Larsson’s Ship and society: maritime ideology in Late Iron Age Sweden.