Here’s one example that took place a year before the Molotov-Ribbentrop pact

The Munich Agreement was an agreement reached in Munich on 30 September 1938, by Nazi Germany, the United Kingdom, the French Republic, and Fascist Italy. The agreement provided for the German annexation of part of Czechoslovakia called the Sudetenland, where more than three million people, mainly ethnic Germans, lived.

Neville Chamberlain and Édouard Daladier made a pact with Hitler to just give him their former ally, Czechoslovakia.