In the ancient-medieval period, imprisonment was used (secure areas of forts), but there was no prison system and no descriptions exist for the internal administration of prisons. With the advent of the British period in India, imprisonment because the most commonly used instrument for penal treatment. In 1897, the Reformative Schools Act was passed to mandate the sending of youthful offenders under 15 years-old to reformative school instead of to prisons. The Indian Jails Committee of 1919 issued a report that gave impetus to prison reforms throughout India and laid the foundation for the modern prison system in India. Recommendations, however, were not implemented in full due to administrative difficulties. The enactment of the Borstal School Acts, Children Acts and Probation of Offenders Act, and Good Conduct Prisoners Probational Release Acts of some States were some of the direct or indirect results of the Committee's report. In the post-independence period, the Government of India sought technical assistance from the United Nations to suggest progressive programs for scientific care and treatment of offenders. One recommendation was the establishment of the Central Bureau of Correctional Services at Delhi and the revision of jail manuals. The All India Conference of Inspectors General of Prisons was held in Bombay in 1952, and it recommended establishing a committee to draft a model prison manual. The Central Bureau of Correctional Services was created in 1961 (renamed the National Institute of Social Defense) to coordinate and develop uniform policy, standardize the collection of statistics, and exchange information with foreign governments and U.N. agencies to promote research and training. Punitive and retributive approaches to corrections have been replaced by the concept of rehabilitation. Open prisons have been established in most of the States.