Little is known about her and how she came into being. But in lore narrated by Sam, at some point King Solomon, when in his reign, learned about the existence of Queen of Sheba and her existence as Nephilim. He later crafted a spell to track her, and succeeded in his endeavor.
At unknown time after, she later married King Solomon afterwards.
The Queen of Sheba is a Biblical and Quranic figure. The tale of her visit to King Solomon has undergone extensive Jewish, Islamic, and Ethiopian elaborations, and has become the subject of one of the most widespread and fertile cycles of legends in the Eastern (Old) World. According to some Islamic accounts, Queen of Sheba was believed to be the descendant of union between a djinni and human, akin to the Supernatural depiction of her as offspring of angel and human.
In lore, eventually, Queen of Sheba married King Solomon and have children, resulting many descendants that eventually become rulers in old countries Saba and Himyar (present day Yemen).