The Nobiliario of Pedro Conde de Barcelos names "D. Alonso Sanchez, El Infante D. Pedro, El Infante D. Fernando Conde de Flandes, El Infante D. Enrique" as the sons of "D. Sancho Rey de Portugal" and his wife "D. Aldonça". The Chronicon Conimbricensi records the birth “in die Sancti Georgii” in 1186 of “Rex Alfonsus filius Regis Sancii et Reginæ Dñæ Dulciæ”. The De Rebus Hispaniæ of Rodericus Ximenes names "Aldefonsum" as the son of "Sancius" & his wife, specifying that he succeeded his father. The testament of “Sancius...Portugaliæ Rex”, dated Oct 1209, appointed “filius meus Rex Donnus Alphonsus” as his heir.
He succeeded his father in 1212 as AFONSO II "o Gordo" King of Portugal and the Algarve. “Alphonsus filius regis D. Sancii et Reginæ D. Dulciæ et nepos regis D. Alphonsi...cum uxore mea regina D. Urraca et filio meo Infante D. Sancio” donated “loco illo...Avis” to its monks by charter dated 1 Jul “Era 1249” [probably misdated]. “Alphonsus...Portugaliæ Rex...cum uxore mea Regina D. Urraca et filliis meis Infantibus Dono Sancio et Dono Alphonso et Dona Eleonor” granted property “in Ansede” to “Gunsalvo Gomes homini meo” by charter dated Jun 1217. The testament of “Alphonsus...Portug. Rex”, dated Nov 1221, appointed “filius meus Infans D. Sancius quem habeo de Regina D. Urraca” as his heir, default to “maior filius quem cunq habuero de Regina D. Urraca...filia mea Infans D. Lianor, quam de ipsa Regina habeo”. He achieved the first systematic compilation of Portuguese law.
The Breve Chronicon Alcobacense records that "Alfonsus" was buried "Alcobacie cum uxore sua domna Urraca filia regis Castelle domni Alfonsi". The De Rebus Hispaniæ of Rodericus Ximenes records that "Aldefonsus" was buried "in Monasterio Alcobatiæ". 1