 The Jesuit historian Eleuterio Elorduy has connected it with Alfonso's voluntary division of his realm in 1154 between his sons Sancho and Ferdinand.Sometime between 1053 and 1065 Ferdinand I had pledged an annual "census" of 1,000 "aurei" to the Abbey of Cluny.This donation was re-established by Alfonso VI in 1077 and then in 1090 increased to 2,000 "aurei" by this same monarch.