García Sánchez I was king of Navarre . Son of Sancho Garcés I, whom he succeeded under the tutelage of his mother, Queen Tota, and his uncle, Jimeno Garcés. Jimena (daughter of Sancho Garcés I and sister of García Sanchéz I) was married to King Alfonso IV of León; For this reason Navarre intervened in the civil wars of the kingdom of León when Fruela II died; this intervention helped Alfonso IV the Monk to triumph.
When Ramiro II, King of León, died, another war broke out over the succession. Queen Tota intervened to put her grandson Sancho on the throne, son of Urraca (daughter of Tota and second wife of Ramiro II); the fight began against the brother of Sancho I, Ordoño III, who took over the throne of Asturias and León; then he was succeeded by Sancho I, who was dethroned by Ordoño IV el Malo in 958; La Tota intervened again, going to the court of the Caliph of Córdoba to ask for his help. Abderrahman III intervened and the usurper Ordoño IV the Bad was dethroned, and Sancho I the Crass placed on the throne again. In 962, García Sánchez I allied himself with the Catalans and Castilians against Alhacam II; but the Navarrese was defeated by the Muslim governor of Zaragoza, who snatched Calahorra from him and forced him to ask for peace, which he maintained until his death in 970 . García Sánchez I was married to Andregoto Galíndez, daughter of Galindo Aznárez (count of the land of Jaca, also called Aragón), which led to the union of the county of Jaca (Aragón) with Navarra in the following reign.