What was the first Olympics to be boycotted by nations that had previously competed?.

Question

The first Olympic flag, presented to the IOC at the 1920 Olympics by the city of Antwerp, Belgium, was lost until 1977. Where had it been?

Answer 1

1980 summer Olympic was boycotted by many nations on the call of USA ,number of actions initiated by the United States to protest the Soviet invasion of Afghanistan.
here is the map, blue nations represents nations boycotted the 198 summer Olympic.