The Libro de Regla of Leire Monastery, compiled in 1076, names "Garseam, Renimirum, Gundisalvum et Fernandum" as the four sons of "Sancius Garseanes…Abarca". “Sancius rex et Ranemirus rex…cum Clara Urraka regina” donated “la villa de Cirueña” to the “monasterio de San Andrés de Cirueña” by charter dated 13 Nov 972, signed by “Sanctius…rex, cum prolis Garseam” confirmed by “Ranemirus frater ipsius regis…domna Urraka Clara regina”. A charter dated 17 Sep 983 confirmed an agreement between Benedicto Bishop of Nájera and the abbot of Albelda, witnessed by "Sancio rex, Urraca regina, Garsea regulus, Ranimirus regulus, Gondesalvus regulus…". “Sanctio principem...cum coniuge mea Urraca et filios nostros Garsea et Ranemiro una cum Gundesabo” granted “villa in territorio Ataresensem...Badagues” to “domno Santio presbiter Ataresense” by charter dated 1 Jan 985. "Sancio, filio Garseani regis…cum coniux mea Urraka et filios nostros Garsea et Ranimiro et Gundisalvo" confirmed a donation to the monastery of Pampaneto by charter dated 6 May 985. “Garssia Santionis rex, Eximinia regina…” confirmed the charter dated 15 Feb 991 under which "Santio Garsseanis rex…cum coniux mea Urraca regina" donated property to the monastery of Leire. "Sancio rex…cum…subole Urraca regina et vina prole Garsea et coniux eius Eximina et Gundessalvo" donated property to the monastery of San Millán de la Cogolla by charter dated 992.
He succeeded his father in 994 as GARCÍA IV King of Navarre, Conde de Aragón. He refused to pay tribute to the caliphate after his accession, triggering reprisal attacks against Navarre. "Garsea rex et uxor mea Eximina, cum domna Urracha regina" donated property to the monastery of San Pedro de Siresa by charter dated to [995/1004]. “Garsea Sancioni rex…cum coniux mea Eximina” donated property to the monastery of Leire by charter dated 31 Dec . 1