According to "Sonpi Bunmyaku" (a text compiled in the fourteenth century that records the lineages of the aristocracy), since it said Tsunemoto died in 961 when he was 45 years old, counting backward from this, his birth year could have been 917.
『尊卑分脈』では961年に45歳で卒去したとある事から、逆算して生年は917年生れとなる。