He was the ninth of the ten illegitimate children of King Alfonso XI of Castile and Lady Eleanor of Guzman.

He was born in Seville. He participated in a revolt of the Castilian nobles against the despotic rule of his brother Pedro of Castile.

In 1373 he married Beatrice of Portugal, daughter of Peter I of Portugal and Ines de Castro. They had two children: Fernando Sanchez, 2nd Count of Alburquerque, and Eleanor of Alburquerque, who married Ferdinand I of Aragon.

He also had an illegitimate daughter, Eleanor Sanchez of Castile.