Complex sentence: At the request of Quiricus of Barcelona, Taius compiled a collection of extracts from the work of Gregory the Great in 653--654, when progress on the compilation was slowed by the revolt of Froia and the invasion of the Basques.
Split into simpler sentences: At the request of Quiricus of Barcelona, Taius compiled a collection of extracts from the work of Gregory the Great in 653--654. In 654 progress on the compilation was slowed by the revolt of Froia and the invasion of the Basques.