Well....early in the 1920s....you had fascism start up in Italy....National Socialism start up in Germany, and Francoism start up in Spain.
Oddly enough....to counter this...at the left side of the spectrum...various social political parties start 'clubs'. Its safe to say both the SPD Party and Communist Party of Germany had elements that were developed as 'thugs'....who were supposed to oppose the bad evil Nazis.
There is a belief as 1932 came along and the Nazis were in charge of the government....this element of both the SPD and Communists....left Germany and spent the next decade in the USSR. After the war, they were set in various ways to return to Germany....as the face of Antifa.
As you go through the 1950s/1960s of Germany, there was class warfare going on, with university students brought into the 'club' of Antifa.
There were various upstarts in France, Italy and across most of Europe in the 1970s and 1980s.....bringing violence as a tool for the 'common working man who was suffering'.
In this era of 2008 to 2020? In a number of cases, the US Antifa attached itself to black inner city, and this puzzled blacks because it was mostly a bunch of educated white intellectual kids....who were into destroying communities. In some odd way, they resembled intellectual klan groups.
Do they have leadership? No. If you find a group of a dozen.....there might one leader of the group, who seems to have cash flow. So far, no one connects the dots....to say a foundation or authority exists.
Interest within the US Marshalls or FBI? That seems odd too.....like they are simply refuse to view them....while spending a lot of time with the Proud Boys.
Final word? As long as they operate in urbanized communities where weapons are frowned upon in open use....they probably will get their strategy done. If they appear in southern communities where weapon use is encouraged....their strategy is doomed.
Whoever brought them to Atlanta....probably isn't from the state of Georgia....just my humble guess.