In Western Christianity, regicide was far more common prior to 1200/1300.[1] Sverre Bagge counts 20 cases of regicide between 1200 and 1800, which means that 6% of monarchs were killed by their subjects.[1] He counts 94 cases of regicide between 600 and 1200, which means that 21.8% of monarchs were killed by their subjects.[1] He argues that the most likely reasons for the decline in regicide is that clear rules of succession were established, which made it hard to remove rightful heirs to the throne, and only made it so that the nearest heir (and their backers) had a motive to kill the monarch.[1]