Towards the end of 1291, King Sancho IV of Castile and Juan Núñez I de Lara, head of the House of Lara, in the effort to forge a political alliance, decided to betroth Alfonso to Juana Núñez de Lara, Juan Núñez I's eldest daughter. He was 5 years old at the time. Alfonso did not survive the year however and the subsequent political alliance fell apart as Juan Núñez I went into self-imposed exile and rebellion against Sancho IV. Alfonso de Castilla y Molina died in Valladolid in 1291 at five years of age.
^ abDel Arco y Garay, Ricardo (1954). "XVI". Sepulcros de la Casa Real de Castilla. Madrid: Instituto Jerónimo Zurita. Consejo Superior de Investigaciones Científicas. p. 271.
Bibliography
Gaibrois Riaño de Ballesteros, Mercedes; Mercedes Ballesteros Gaibrois (1922–1928). Revista de achivos, bibliotecas y museos (ed.). Historia del reinado de Sancho IV de Castilla. Madrid: Editorial Voluntad. 5332259. 3 volúmenes
De Loaysa, Jofré; García Martínez, Antonio (1982). Crónicas de los Reyes de Castilla Fernando III, Alfonso X, Sancho IV y Fernando IV (1248-1305) (in Latin and Spanish) (2nd ed.). Murcia: Academia Alfonso X el Sabio. ISBN84-00-05017-7.