SANCHO García de Castilla, son of GARCÍA I Fernández Conde de Castilla & his wife Ava --- ([965]-5 Feb 1017, bur San Salvador de Oña). "Garcia Fredinandiz, Aua comitisa" donated property to the monastery of Cardeñas by charter dated 11 Jul 972, subscribed by "Sancius prolis illorum, Domna Fronilde…"[210]. "Garsia Ferdinandi comes et imperator Castelle, Abba uxor Garcia" executed a charter dated 8 Mar 974 relating to property at Castrojeriz, witnessed by "Sancio filio nostro, Urraca filia nostra…"[211]. "Garsea Fredinandiz comes, Aua comitisa" executed a charter dated 24 Nov 978 consecrating "Urraca filia nostra" at the monastery of Covarrubias, confirmed by "Sancio Garsea, Gundisalbo Garsea…"[212]. He rebelled against his father in 990, supported by Ibn Abu Amir[213], effectively dividing Castile into two parts. The Annales Complutense record that "Sancius Garsia" rebelled against "patrem suum comitem Garsia Fernandez" in 990[214]. He succeeded in 995 as Conde de Castilla. "Sancio comite et Urraca cometissa soror mea" granted rights to the monastery of San Millán de la Cogolla by charter dated 1003, signed by "…Fernando Beilaz, Oveco Alvarez, Beila Alvaroz, senior Assur Nunniz dominate Ponticurbo, Alvaro Gomiz, Tellu Didaz, Beila Gutier"[215]. He allied himself with the Berbers in 1009 to fight and depose Caliph Muhammad. The Chronicon Burgense records that "comes Sancius" destroyed Córdoba in 1009[216]. He was given a formal reception in Córdoba by the new Caliph Sulayman, and received strategic castles as his reward. He opposed the rise to power of Menendo González, as regent for the infant Alfonso V King of León, which led to many conflicts with León[217]. The Chronicon Burgense records the death in 1017 of "comes Sancius"[218].
m ([985/95]) URRACA, daughter of (-[murdered Covarrubias] after 21 Dec 1037). "Sancius comes cum coniuge mea Urracha" offered "filiam nostram Tegridiam" to the monastery of San Salvador de Oña by charter dated 12 Feb 1011[219]. Her parentage is not known. Salazar y Acha suggests that she was Urraca Gómez, daughter of conde Gómez Díaz de Saldaña & his wife Muniadomna Fernández de Castilla[220]. He bases this especially on the introduction of the name Tegridia into the family of the condes de Castilla, the name of the mother of conde Gómez Díaz. Regent of the county of Castile during the minority of her son. The Annales Complutense record that "comitissam Urracam" was killed (by Muslims) "in Covas Rubias" in "Era 978 (940)"[221]. The date is clearly incorrect if this entry refers to the widow of Conde Sancho but it is possible that it is misplaced by a century. The Anales Toledanos record that "la Condesa Doña Urraca" was killed "en Cuevarrubias" in 1038[222].
Conde Sancho & his wife had five children