with a pod no earlier than 1492 make three empires rule 80% of the planet by the end of the 1900, with possibly a few vasal states or indirectly ruled dominions and inipendant or semiautonomus enclaves.
one of the three can be a federation of states, and nider have to be actual official empires, but all of their territory should be ruled by one political faction and this faction such as a ruling party or monarchy, and should have next to total controll of economy and politics, with minimal resistance, but all this is flexible
one or all can be apsolutist monarchies
or anithing in betveen
olny rules are no roman empire wank, and no uber south africa wank, and at least one must be a theocracy, preferably catholik, a muslim theocracy is a bit obvious, but will do