Vikings met up in the Black Sea and the Mediterranean after traveling their from both the Atlantic and the Volga River.
Where is the surprise that a Viking brought home a souvenier?
In addition, the Arabs had plenty of gold and silver loot, and, at the time, had the best coinage. Arab coins have been found from China to Africa to Northern Europe.
It is actually no surprise at all.
The author of this article seems ignorant of he fact that Vikings (known in the Middle East as "Varanger") were hired by the Byzantine Emperors as bodyguards and mercenaries.
I can only copy a portion of the following text by Colin Low, as it is copyrighted material. (It's actually part of his research paper on the Necronomicon.) But for a taste of what he has written, here's a "Fair Use" excerpt:
"The popular image of Vikings in furry jerkins and horned helmets is inaccurate. They were among the best equipped and most experienced heavy infantry available at that time. Their trade routes spanned thousands of miles, from North America, to Greenland, Britain and Ireland, the entire Atlantic coast of Europe, and through Russia to Byzantium. They were employed in significant numbers as bodyguards (Varanger) to the Byzantine emperors. Most Varanger spoke fluent Greek. The exact year in which Harald went to Byzantium is unclear due to a minor mismatch between Norse and Byzantine sources, but the account in the Heimskringla claims he served the Empress Zoe the Great sometime around 1030-40. The description of their arrival in longships is spell-binding:
"Iron shielded vessels
Flaunted colourful rigging.
The great prince saw ahead
The copper roofs of Byzantium;
His swan-breasted ships swept
Towards the tall-towered city."
It was the custom in those days that when the Emperor died, the Varanger were permitted to plunder the palace and anything they laid hands on, they could keep. These were turbulent and violent times (with the Empress Zoe strangling husbands in the bath) and Harald took part in three such plunders. According to the chronicle he amassed great wealth."
Indeed the real surprise is not that Arabic trinkets are found, but rather that they are not found in far greater numbers.
An Italian captive. The faded ring actually said, “I lova you for allah time!”