Anybody familiar with the 1972 Munich Olympics massacre knows about the Palestinian terror group “Black September,” which was active in the early 1970s. Black September, the organization, was either a faction within or a splinter off of Yasser Arafat’s Fatah party that specialized in terrorist attacks on an international scale (by which I mean in places outside of Israel-Palestine). Depending on whose version of the story you believe, it either operated independently of Fatah or its purpose was to carry out especially violent while still giving Fatah and the PLO deniability. Either way, the group disbanded in late 1973/early 1974 when the PLO decided to put the kibosh on international terrorism.
In its earliest incarnation, Black September the organization was a reaction to Black September the event, which began on September 16, 1970 in Jordan. Effectively a civil war between the PLO and Jordan, Black September had a fairly significant impact on the Palestinians and on the region.