Algerian authorities list age, neglect and overpopulation as the principal contributors to the degeneration. Overpopulation makes the problem especially difficult to solve because of the effort it would take to relocate the residents. Estimates range from 40,000 to 70,000 people, although it is difficult to be certain due to the number of squatters in vacant buildings. One reason that the government wants to improve the condition of the Casbah is that it is a potential hideout for criminals and terrorists. In the late 1950s and during the civil insurrection and struggle against French colonial rule it was the hideout for the National Liberation Army (Algeria).