King Jinpyeong, having no sons, selects Princess Deokman as his heir.

The act is not unusual within Silla, as women of the period had already had a certain degree of influence as advisors, dowager queens, and regents.

Throughout the kingdom, women are heads of families, since matrilineal lines of inheritance exist alongside patrilineal ones.

During the Silla kingdom, the status of women is relatively high, but there are still restrictions on female behavior and conduct; they ware discouraged from activities considered unwomanly.

Her successful reign will in turn facilitate the acceptance of two more Queens regnant of Silla.

Jinpyeong dies in January 632, in the fifty-fourth year of his reign, and Princess Deokman becomes, as Queen Seondeok, the sole ruler of Silla.

According to the Samguk Sagi, she was the first of King Jinpyeong's daughters.

But according to another historical record, she was the second of King Jinpyeong's daughters and much younger than her elder sister (Princess Cheonmyeong).

Her nephew, Princess Cheonmyeong's son, will eventually become King Muyeol of Silla while Seondeok's other sister, Princess Seonhwa, will eventually marry King Mu of Baekje and become the mother of King Uija of Baekje.

Seonhwa's existence is controversial due to the discovery of evidence in 2009 that points to King Uija's mother as being Queen Sataek, and not Seonhwa as indicated by historical records.