<human>:  When did Eastern Orthodox iconoclasm start?
<bot>: Eastern Orthodox iconoclasm started in the 8th century. The Orthodox Church had been around since the 4th century, and had already established a tradition of icon painting. In the 8th century, the Byzantine emperor Leo III the Isaurian ordered the destruction of icons. This was the beginning of a long and painful process that would eventually lead to the destruction of many of the most beautiful and important religious icons.