What deal did Neville Chamberlain and Hitler make?

Neville Chamberlain and Adolf Hitler agreed to the Munich Agreement in September 1938, which allowed Nazi Germany to annex the Sudetenland region of Czechoslovakia in exchange for a promise of no further territorial expansion. Chamberlain believed this concession would secure peace in Europe, famously declaring that the agreement would bring "peace for our time." However, the deal ultimately failed to prevent World War II, as Hitler continued his aggressive expansionist policies.