In 1972, concerned about the influx of foreign culture into Nigeria, the "Indigenization Decree" was issued by the then head of state Yakubu Gowon; which demands the transfer of ownership of about a total of 300 film theatres in the country from their foreign owners to Nigerians. Also, more Nigerians started playing active roles in cinema establishment as a result of this policy. This transfer also resulted in the emergence of Nigerian playwrights, screenwriters and film producers; popular literature and theatre works were adapted into motion pictures. The oil boom of 1973 through 1978 contributed immensely to the spontaneous boost of the cinema culture in Nigeria. The presence of foreign investments led to the erection of several cinema complexes. In 1976, The 5000-capacity National Arts Theatre, Iganmu was constructed in Lagos. The theatre was incorporated with two cinemas, each having a capacity of over 700 people. At this time cinema business had become a notable employer of many people and also served as an important social function, as Nigerians visited cinemas for relaxation and entertainment purposes. The increased purchasing power in Nigeria also made a wide range of citizens to have disposable income to spend on cinema-going and on home television sets.