+644 was a [common year](/wiki/Common_Year) of the [Julian calendar](/wiki/Julian_Calendar) in the 7th century. It saw significant events in the early Islamic world, notably the assassination of the second Rashidun Caliph.
+## See also
+- [Islam](/wiki/Islam)
+- [Caliph](/wiki/Caliph)
+- [Umar](/wiki/Umar)
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