"The murder of Hussein occurred in Southern Iraq, near the city of
Karbala. He was murdered together with several dozens of his friends and
family members, with only one baby surviving to continue the dynasty.
The murder, which occurred in 680 - remains the defining event for
"Shi'at Ali", the "sect of Ali", which is the source of the name "Shia"
or Shi'ite, the name of the stream of Islam that supports the leadership
of Ali's descendants."
"This family conflict has been ongoing for almost 1400 years."
All the gory details are in the article, and it is an excellent summary of why Israel and Saudi Arabia are strange "frenemy" bed fellows right now.