叫你说中了
I said these were the policies available for everyone, but as some may have gathered from screenshots and dev diaries, we are taking quite the shining to the Islamic world in 1.23. As such, there is a specific Trade Policy available to Muslims: Propagate Religion.
When a Muslim nation controls more than 33% of the Trade Power in a Trade Region's node, they are able to activate the Propagate Religion Trade Policy, which will establish a Religious Centre in the node, spreading this religion within the node, as can be seen in my totally legit Omani screenshot