Ideologically, Wahhabism takes the embrace of God’s oneness and avoidance of shirk as its main point of emphasis, so it’s no wonder that Ibn Abd al-Wahhab embraced what Ibn Taymiyah had to say about the treatment of saints and their shrines. He went further though, arguing that Shiʿa were guilty of elevating their imams over Muhammad and even of placing them on the same level with God. And under the so-called “First Saudi State,” which lasted from 1744 to 1818 and grew to control most of the Arabian peninsula during its brief lifespan, these tenets of Ibn Abd al-Wahhab’s teaching were made state policy.
This all explains why, on April 21 in either 1801 or 1802, but more likely 1802, a Saudi army of about 12,000 men marched north to Karbala, destroyed the Imam Husayn Shrine (seen above in its modern form), and massacred between two and five thousand people in the process. Or, well, it explains their theoretical justification for carrying out that attack. If you ask me, the reason for the raid on Karbala was much less about fighting for the One True Islam than it was about all the sweet loot they were able to plunder.