Complex sentence: He said that was a Basque custom to name a place after its location, for Bilbao this would be the result of the union of the Basque words for river and cove: "Bil-Ibaia-Bao".
Split into simpler sentences: He said that it was a Basque custom to name a place after its location. For Bilbao this would be the result of the union of the Basque words for river and cove: "Bil-Ibaia-Bao".