Question: When was Beatrice Of Castile, Marchioness Of Montferrat's mother born?
Sentence (from "Beatrice of Castile, Marchioness of Montferrat"): Beatrice of Castile (5 November or 6 December 1254 - 1286) was a daughter of Alfonso X of Castile and his wife Violant of Aragon.
Relevant evidence: Yes