The Hand Of Night - (1966)
British 'B' movie – from the description: A tourist to Morocco "travelling through the desert comes at night upon a Moorish castle where he is entertained by a mysterious wealthy woman. He departs and returns in the morning to find the place has vanished." (No it hasn't, it's old ruins.) "His inquiries only bring fear and hostility from the locals. He gradually finds himself lured into a deadly and sinister supernatural mystery."
Apparently (according to one character in the movie) from an Islamic concept of light and dark = good vs evil, and originated in Persia, and is spookily similar to The Force in Star Wars ... who would have guessed ...