Despite the obvious similarity to Saracen, the place-name is likely derived from serkr (gown, modern Swedish "särk") and land (land, country), referring to the clothes of the people that lived in the area. Another possible explanation is the Turkic word for "forty furs", which was an important currency during the Viking Age and resulted in the modern Russian word for "forty" - sorok. It could also be related to Sarkel, a city located in the territory of the Khazars.
^Jesch, Judith. Geography and travels. In : Old Norse-Icelandic literature : a critical guide. Ed. by Carol J. Clover and John Lindow. Toronto ; London : University of Toronto Press in association with the Medieval Academy of America, 2005. (Medieval Academy reprints for teaching ; 42). P. 125. ISBN 0-8020-3823-9.