The last census in The Netherlands, in 1947, delivered per municipal the number of persons with the familyname Van Santen (2269)respectively Van Zanten (3482) [Meertens].
Here they are mapped.
4.4% of the Van Santen's and 9.7% of the Van Zanten's in the Netherlands lived outside this area of 145 x 100 km.
The area in a circle is linear with the number of persons; the top four are drawn heavier.
The numbers in the centers indicate domiciles, used in [Meertens].
The cross indicates the center of all persons with the name in the Netherlands.
The biggest concentration is in the Westland, south of The Haque.
The extention of that probably original area could be inland only.
A recent census will show a more diffuse map due to the since 1947 raised mobility.