My maternal great(or, possibly, great-great) Aten grandparents immigrated to the United States around 1880 from Holland, near the town of Assen, which is not far from the Rhine river. They were Jews, but as far as I can tell, they were probably Sephardic Jews. As far as my grandparents knew, Aten is a Jewish name, tho my grandparents converted to Methodism upon arrival in the States in an attempt to assimilate.
I would say that Aten is a Sephardic Jewish clan which most likely fled the the Spanish Inquisition to Holland, which at the time was a fairly open country, if you had any skills and weren't an Ashkenazi Jew. My Aten ancestors in Holland were carriage and harness makers.
From what I have gathered so far, "Aten" is most likely a West Semitic name, possibly related to the Egyptian word Aton (Aten, Atumn, Atom) which is one of the names of the Sun. Most Sephardic names are West Semitic rather than East Semitic which reflects a historical relationship closer to Egypt than to Sumeria. If you recall, Solomon's Kingdom was a (attempted) unification of two kingdoms, one of western semitic Egyptian Hebrews and Levites and the other of eastern semitic Mesopotamian Jews (the Children of Abraham).
It is entirely possible that other Dutch families also used a family name that was coincidentally spelled "Aten." My family, however, were definitely Jewish, most likely Sephardic Jews from Spain.
Why the obscurity? Possibly because Sephardic Jews began emmigrating to Western Europe very early on, even in pre-Roman times. The first Sephardic immigrants may have arrived in Spain and Portugal on the heels of the Phoenicians and Etruscans. There was a sizable Jewish or Hebrew population living in Rome before the Caesars. Because they left Palestine before the forced Dispersions under the later Romans and Arabs, Sephardic Jews tended to assimilate more into Western European society and to be less closely identified with Rabbinic (Ashkenazi) Judaism. Sephardic Jews even served as senior Catholic Church leaders in Spain, Portugal, France, and Italy.
As an interesting footnote, Sephardic Jews from Portugal and Spain were among the first settlers in the New World, especially in Brazil. Many of them switched allegiance to Holland in the seventeenth century and some resettled in New Amsterdam (New York) in the seventeenth and eighteenth centuries, again, ahead of the Spanish Inquisition.