 In a papal letter dated 7 May 1078 Gregory confirmed that he was sending Cardinal Richard to Castile "as the King of Spain has asked and your counsel has desired" ("sicut rex Hispaniae rogavit et vos consilium dedistis").Alfonso had already been described as "King of the Spains" ("Hispaniarum rex") in a letter to Hugh of Cluny on 10 July 1077.Other possible incentives for Alfonso to stress his hegemony over the Iberian peninsula include the submission of most the "taifas" (Islamic factional kingdoms) to his suzerainty by the payment of "parias" (tribute) by 1073, and the annexation of La Rioja and those parts of Castile belonging to Navarre after the assassination of Sancho Garcés IV in 1076.