Well, she could have been from a distant land from which we have no record or she could have been invented to give an air of impressive authority to a Solomon who may, himself, be partially or wholly legendary. What Velikovsky has done is to transport all of Hebrew history and Egyptian history to a temporal location that is not supported by any evidence beyond his need to reconcile one unattested story with a different story. He could be right, but lacking anything resembling a coherent testimony (since his time shifting requires that all his other disproven physical situations had to have occurred), there is no reason to believe it and, really, no reason to try to find supporting evidence.
Which may just be because the Exodus (in any form that we would recognize) never occurred.