Ancient kingdom of the Sabeans (5)
I believe the answer is:
sheba
'ancient kingdom of the sabeans' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for sheba that I've seen before include "Biblical Queen of . . . . . visited King Solomon" , "Solomon was visited by this country's queen" , "Its queen arrived" , "Old Yemen kingdom, its queen visited Solomon" , "land of noted royal arrival" .)