Klephts (Greek κλέφτης, pl. κλέφτες - kleftis, kleftes, "thieves") were bandits who lived in the Greek countryside when that country was a part of the Ottoman Empire. They were generally men who were fleeing the Turks, vendettas, taxes, or debts. They raided other travellers and isolated settlements. They lived in the rugged mountains and back country. Most klephtic bands participated in some form in the Greek War of Independence.
After the fall of Constantinople in 1453 and then Mystras in the Despotate of the Morea, Greece was entirely in the hands of the Ottoman Empire, save for a few island and coastal possesions of Venice. This situation lasted until at least 1821 (although some parts of Greece remained in Ottoman hands until the 20th century) and in Greece is known as the Τουρκοκρατία -- "Turkocracy."
Ottoman conquests were divided up into pashaluks (provinces); in the case of the lands that form modern Greece, these were Morea and Roumeli, which were further sub-divided into feudal chifliks (Turkish çıflık, Greek τσιφλίκι). Any surviving Greek troops, whether regular Byzantine forces, local militia, or mercenaries had either to join the Ottoman army as janissaries, serve in the private army of a local Ottoman notable, or fend for themselves. Many Greeks wishing to preserve their Greek identity, Orthodox Christian religion, and independence chose the difficult but liberated life of a bandit. These bandit groups soon found their ranks swelled with impoverished and/or adventurous peasants, societal outcasts, escaped criminals, and even occasionally renegade Turks.
"Wild" klephts and "tame" klephts
It would be incorrect to think of the klephts in quite the same terms as modern urban gangsters such as Al Capone. The klephts had more in common with the early Mafia of the Sicilian Vespers, or other outlaws like Pancho Villa and Rob Roy and mixed the politics of national liberation with quests for personal revenge, enhancement of clan status, and personal profiteering. Actually, their main cause was often merely survival in the barren mountains of Greece and Albania.
Many klephts would spend part of their lives in service to Ottoman landowners, some of whom were Turkish colonists and others native Greeks who had either kept their position after the Turks invaded, or were from Phanariot families who received grants of land from the sultan. Klephts who worked in this capacity were referred to as "tame klephts" while those who were independent were known as "wild klephts."