king of Navarre (Navarra) (Pamplona) from 1150 and son of García IV (or V) the Restorer.

Sancho was the first to be called king of Navarre; previous kings were known as kings of Pamplona. In 1151 Castile and Aragon signed at Tudillén a treaty for the partition of Navarre. By skilled diplomacy Sancho avoided the destruction of his kingdom, accepting Alfonso VII of Castile as his overlord and marrying Alfonso's daughter. He himself intervened in Castilian affairs during the minority (1158–70) of Alfonso VIII. In 1176 both countries submitted their longstanding territorial disputes to Henry II of England as arbiter, who assigned Rioja to Castile. Sancho accepted this decision. He was a legislator of importance, conceding many municipal fueros (fuero) (charters) and protecting Jews and immigrants (francos) from the north.