His existence is known from two sources: one is a mummy-label found on the mummy of his daughter Nebetia, where he is mentioned as her father; the other is a Saqqaran relief of his tutor, Meryre, where a person named Siatum is depicted sitting on Meryre's knee.
Siatum's existence is documented through two sources: a mummy-label found on the mummy of Nebetia, which identifies him as her father; and a Saqqaran relief depicting him sitting on the knee of his tutor, Meryre.