The Rietlanden was the shunting yard of the Dutch Railways. In the first months of 1943, many transports left for Westerbork, especially with sick and elderly people, from this shunting yard.
As a prohibited area, "Sperrgebiet", this was the ideal place to deport Jews. No one was allowed to enter without permission and the activities of the Nazis were therefore not noticed. Therefore, the exact number of people who were deported from this location is not exactly known, it was certainly many thousands.
See also source: website www.joodsamsterdam.nl/Borneokade about deportation from a secluded spot in the Eastern Docklands of Amsterdam. or Ons Amsterdam Magazine published May 2010 "van Rietlanden naar Westerbork. (both items Dutch language only)