 King Mongkut (Rama IV) (1804-1868) stimulated interest in naming babies in accordance with astrological principles as outlined in the ancient scripture, "Namtaksapakorn".During the time of Field Marshal Plaek Phibunsongkhram (1897-1964), gender-based naming was introduced.Names ending in "-sak", "-chai", and "-yot" were for male babies, "-porn" or "-sri" for females.