I'm afraid this is not very good, as it is... It could be fixed though, and expanded to be less England-centric too ;) (I'm thinking of Otto I, Clovis, Francis of Assisi...).
First, you have to correct the Gregory one... The calendar is due to Gregory XIII, during the 16th century.
The Charlemagne one doesn't seem correct. He conquered much more than France, and I think it's bold to credit him with the invention of feudalism.
Some of the others are inaccurate (like the Justinian one) or a bit cliché. You really should read more about those people to make better clues.
I suggest to show more complete names: Geoffrey Chaucer, Hildegard of Bingen, William the Conqueror ; and to accept more type-ins (especially for Muhammad).
No-one describes or thinks of William the Conqueror as 'Viking' except by a loose ancestry association. He was a Norman. Justinian started his own empire? And Wrong Gregory!
The Viking King (from Denmark) who conquered England was Cnut, some 50 years before William (from Normandy) invaded England in 1066. The Normans and Vikings were not the same.
First, you have to correct the Gregory one... The calendar is due to Gregory XIII, during the 16th century.
The Charlemagne one doesn't seem correct. He conquered much more than France, and I think it's bold to credit him with the invention of feudalism.
Some of the others are inaccurate (like the Justinian one) or a bit cliché. You really should read more about those people to make better clues.
I suggest to show more complete names: Geoffrey Chaucer, Hildegard of Bingen, William the Conqueror ; and to accept more type-ins (especially for Muhammad).