Those With Black Hand were Sauron's main and most loyal group of agents in southwestern Middle-earth. Though they were in fact the religious wing of the Army of the Southern Dragon, they did not appear openly militant or violent, but rather as wandering Prophets. However they would at any time have chosen different methods had there not been powerful competitors such as the Servants of the real fire or the Cult of the dark Overlord who already were known for their ruthlessness and insidiousness, which gave the Hands much motivation to distinct themselves.
They were however quite evil and their numbers presented a great danger to the Free Peoples or rebels of southwestern Endor. Known And reviled throughout the Seven Lands, they were often referred to as "Hands". Of course, wiser folk spoke of them in veiled whispers. The main center of Black Hand was located in Fal Carth, a city known for (and protective of) it's diverse religions. From this base the Hands preached of the power of the High-king of Men (Sauron of Mordor). Naturally, the Black Hand served as their symbol.