He was the eldest son of Gómez Díaz [es] and Muniadomna Fernández, daughter of Fernán González, Count of Castile.
[1] Leagued with Almanzor, the Muslim hajib, who marched on León, the rebels forced Vermudo to take refuge in Galicia and expelled the counts of Monzón from the Tierra de Campos.
[2] The entire land between Zamora and Castie, including León itself, was in the hands of García, governing under the authority of Almanzor.
[6] The only narrative Christian sources to mention the battle, both closely related to the Muslims histories, differ from them in stressing the leadership of García Gómez.
The Anales Castellanos Segundos record that In era MXXXVIII [año 1000] fuit arrancada de Cervera super conde Sancium Garcia et Garcia Gomez: "In the Era 1038 [AD 1000] was the defeat of Cervera over count Sancho García and García Gómez.