Don't know if this is in the manual, but the religion of the CoT's owner makes a huge difference in the size of that CoT. I've found that Catholic >> Sunni >> Pagan. For example say you have three adjacent nations, #1 has a Moslem CoT, #2 belongs to a nation without a CoT, #3 has a Catholic CoT. The Catholic CoT will completely take over the neutral nation - the Moslem CoT can only keep its own nation. If you replace the Moslem with a Pagan, the Catholic will also incur into the Pagan nation. I think Protestant CoTs are only slightly better than Catholic ones - the big difference is between Christian and Moslem (and Pagan). This explains why China loses nearly all and India (Moslem) some of its CoT area when a Christian CoT opens up.