Sheba is normally taken to be 'Saba' - in Yemen in southwest Arabia. It was often argued that it should be in the northwest of Arabia, but there is nothing mentioned in any texts of a kingdom called Saba up there, but they do mention a lot of other kingdoms. Assyrian sources mention Sabean caravans travelling north around the 8-9th centuries, just after Solomon's time period.

Whether she's a queen or not is up for grabs - she could have been a consort sent out as an ambassador (north Arabian queens did this), and there are accounts of women occupying positions alongside men during the period. Queens with executive power exist in North Arabia between the 7-9th centuries BC but not afterwards, and their existence in historical terms seems to disappear between 690BC to 570AD - (only one queen is mentioned in any historical setting during this period and that was about a kidnapping).

In short, we have queens who took on roles as described in the story, but all our evidence is North Arabian. If the same goes for the South, there's no reason why the story couldn't have happened. The fact that their activity in history disappears after 690BC indicates that the story might be old, and fits the 8-9th century information we have about North Arabian queens.

There quite a substantial section of ANE scholars who argue that Solomon wasn't real and so the story must have been made up, but that's another question. There's nothing to preclude either her activity or her existence, but we simply do not have enough data to be certain.