The Oliphants were mobile in shipping, going abroad for education, etc., going back over 500 years. Thus the Oliphant surname spread throughout Europe. Here's a board to discuss the European Oliphants.
I have no idea how many Oliphants there are in the rest of Europe - I suspect that the name has even been corrupted - I wondered when I saw this: Oehlhafen (say it phonetically fast) - there really are people with that name - are they related? Who knows.
As for England, so many Oliphants have gone south of the border into England and then proliferated. Extensive DNA testing would be hugely revealing, grouping them into their original families in Scotland. I would urge them all to participate in the DNA project.
There is a very good chance that Duncan Oliphant came to Staten Island from Holland and was either part of the wool staple or the military. He lived among the Dutch in the north precinct of S.I. and was elcted constable in 1709. He used Dutch Godparents for his daughter, Margaret's, baptism in 1709 and served as a witness to a Dutch baptism c. 1713. He moved his family to Amwell Township in Hunterdon Co. NJ in 1721. He was well educate and carried a family which he affixed to legal documents, including his will. He also has a book of law called "The Conductor Generalis"