Complex sentence: The first mention of Corfu (known as Corcyra at the time) was written by Herodotus, who said that Corcyra was a colony of Corinth, and that from the foundation of this colony, Corfu and Corinth ceased to agree.
Split into simpler sentences: The first mention of Corfu (known as Corcyra at the time) was written by Herodotus. Herodotus says that Corcyra was a colony of Corinth, and that from the foundation of this colony, Corfu and Corinth ceased to agree.