I want to know the answer to the following question:
After what time did the Abbot of Monte Cassino send for Byzantine mosaicists?
All the background I'm provided with is that ""The abbot in his wisdom decided that great number of young monks in the monastery should be thoroughly initiated in these arts" – says the chronicler about the role of the Greeks in the revival of mosaic art in medieval Italy.". Is that enough to answer the question?