Parsha Korach may seem to the reader to be a logical continuation of Parsha Shelach as it would seem very much that Korach and his attempted power grab is a logical after-affect, a consequence of the denial of Eretz Yisrael by 10 of the 12 miraglim (spies).
In fact, Yehuda Nachshoni’s “Studies in the Weekly Parsha” (pages 1032-1033) cites Ramban’s view that the cause of the rebellions of our Parsha; Korach’s, Dasan and Aviram’s and the First Born’s was: