The modern state of Yemen is located on the southwest corner of the Arabian Peninsula, just a plank-walk across the Gulf of Aden and Red Sea from Africa
Until 1990, Yemen was divided into two independent states: North Yemen and South Yemen. Both states were established in the late 1960s...before that, North Yemen had been an independent kingdom, until it was upended by a Nasser-led civil war that began in the 1960s. South Yemen, formerly known (in part) as the protectorate of Aden, had been under the control of the United Kingdom (it was one of the last, flickering lights of the glory that used to be the British Empire).
Now that we've differentiated between the two Yemens, forget all about the South. North Yemen is the setting for our story.