The inaugural Singapore Grand Prix was held from the 9th to 11th in April 1966, on the Thomson Road Grand Prix circuit. Previous editions of the Grand Prix were held before Singapore gained its independence, and were not called Singapore Grand Prix. The 1965 Malaysian Grand Prix was held on the same course, as part of the Malaysian Grand Prix event, as the 1966 Grand Prix of Singapore.
1966 Singapore Grand Prix Wikipedia
1966 1ST SINGAPORE GRAND PRIX
Thomson Road Grand Prix circuit
April 9–11, 1966