His existence is corroborated by the chronicle of Ibn Hayyan, which describes how he was a supporter of Ramiro II King of León in the civil war with his brother ex-King Alfonso IV, and how his brother and son-in-law were killed in an attack in 932. "…Gutier Menendiz, Arias Menendiz, Flaginus Didaz…" subscribed the charter dated 5 Jun [892] under which Ranulfo Bishop of Astorga donated the church of Villanueva de Valdueza to San Pedro de Montes. “...Garsea Furtuniz, Flainus Didaci, Gisiuadus...” confirmed the charter dated 9 Jan 916 under which King Ordoño II donated "locum...Ualle Cesarii" to “abbati Seruando”. “...Garsea Furtuniz, Flainus Didaci, Gisiuado maiordomus, Braulio, Lup iben Alcutia...Fortis prolis regis” confirmed the charter dated 8 Jan 917 under which King Ordoño II donated "locum...Perameno" to “confessoribus...Transmundo et Recesuindo”. "…Guter Osoriz, Guter Menendi, Arias Menendiz, Flaginus Didaz, Fredinandus Didaz…" confirmed the charter dated 24 Apr [918], probably spurious, under which "Ordonius rex et Giloria regina" donated el Coto de Valdueza to the monastery of San Pedro de Montes.
Conde: the dating clause of a charter dated 943, under which "Abofetha et Cisla" donated property to the monastery of San Martín de Albelda, names "regnante principe Garseani in Pampilona, et comite Flagino in Vecharia…". "Garsea rex…cum genitrice Tuta regina" donated property to the monastery of San Martín de Albelda by charter dated 22 Nov 947, witnessed by "…Flaginus comes…". Tudemiro Bishop of Nájera donated property to the monastery of San Martín de Albelda by charter dated 22 Nov [947], confirmed by "…Flaginius comes, Garsia comes…". 1
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