when were they laid down?
Between 1947 and 1949.
Fundamental Rights, Directive Principles and Fundamental Duties of India
 1947 and 1949
directive principles of state policy over fundamental rights They are not enforceable in any court of law, declares them to be "fundamental to the governance of the country" and imposes an obligation on the State to apply them in matters of legislation.
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Fundamental Rights, Directive Principles and Fundamental Duties of India [SEP] Introduction
The Fundamental Rights, Directive Principles of State Policy and Fundamental Duties are sections of the Constitution of India that prescribe the fundamental obligations of the states to its citizens and the duties and the rights of the citizens to the State. These sections comprise a constitutional bill of rights for government policy-making and the behaviour and conduct of citizens. These sections are considered vital elements of the constitution, which was developed between 1947 and 1949 by the Constituent Assembly of India. The "Fundamental Rights" are defined as the basic human rights of all citizens. These rights, defined in Part III of the Constitution, applied irrespective of race, place of birth, religion, caste, creed, or gender.