 The Thai terms for dance, รำ "ram" and ระบำ "rabam", derive from the Old Khmer words រាំ "raṃ" and របាំ "rapaṃ" respectively.The multitude of Khmer words relating to dance, music and performance and similarities between the gestures of Thai dance depictions of dancers in ancient Khmer sculpture and bas reliefs suggests extended influence of ancient Khmer forms on Thai classical dance and performance.According to Surapone Virulrak, Thai performance art took shape during the Ayutthaya period, where "Chak nak Dukdamban", a "ceremony depicting the churning of the ocean to create the immortal spirit, was performed on special occasions."