Mujahadeen

Mujahideen (Arabic: مجاهدين‎‎ mujāhidīn) is the plural form of mujahid (Arabic: مجاهد‎‎), the term for one engaged in Jihad. In English usage, it mostly referred to the guerrilla type military outfits led by the Muslim Afghan warriors in the Soviet–Afghan War, but now it often refers to other jihadist outfits in various countries.

In its roots, Mujahideen (an Arabic word) refers to any person performing Jihad. Jihad was the term used for the project of Islamic conquest in the early history of Islam, during the medieval era led by the caliphates (7th through 9th century). In its post-classical meaning, Jihad refers to an act which is spiritually comparable in reward to promoting Islam during the early 600s CE. These acts could be as simple as sharing a considerable amount of your income with the poor. Some Islamic sects believe that armed-conflicts cannot be branded as Jihad unless it has been ordered by Messiah.

The modern term of mujahideen referring to guerrilla outfits radical Islamists originates in the 19th century opposition of the mountainous sect of hill men in Afghanistan who fought against British control (although initially to the British they were known as Sitana Fanatics). It began in 1829 when a religious man, Sayyid Ahmed Shah Brelwi, came back to the village of Sitana from a pilgrimage to Mecca and began preaching war against the infidels in the area defining the Northwest border of British India. Although he died in battle, the sect he had created survived and the Mujahideen gained more power and prominence. During the Indian Mutiny of 1857, the Mujahideen were said to accept any fleeing Sepoys and recruit them into their ranks. As time went by the sect grew ever larger until it was raiding and controlling larger areas in Afghanistan.

...
Wikipedia