Etheria (circa 4th century CE) wrote, "The whole mountain group looks as if it were a single peak, but, as you enter the group, [you see that] there are more than one."[54] The highest mountain peak is Mount Catherine, rising 2,610 metres (8,550 feet) above the sea and its sister peak, Jabal Musa (2,285 m [7,497 ft]), is not much further behind in height, but is more conspicuous because of the open plain called er Rachah ("the wide"). Mount Catherine and Jabal Musa are both much higher than any mountains in the Sinaitic desert, or in all of Midian.