Did you go for low or high piety? And I assume you fought wars constantly on multiple fronts? How did you manage that with a limited number of troops?
Also, did you get PUs over anyone, like Crimea? How did you expand into the hordes?
West Africa is easy as long as you get exploration which I skiped and got expansion too late, in my game literally every european power put 1-2 of their colonys on the shore so would have been a pain fighting each one for just 1-2 provinces, or maybe I was just too lazy for it.
Inner parts are also easy, Mali and the other locals can't really do anthing against you and it shouldn't generate that much AE with the europeans, however by the time I got a border with Mali they already cleaned up the place and with nations losing their cores as of now would have had to manually core it all.However if you get exploration early and colonise the shore should be able to grab west africa with little to no effort, just didn't think of it much when starting this game.
As for Piety, go for high piety for easy conversion, think I had a missionary working all the time with no pause cause of all the christan/hindu/confucian/buddhist provinces I had to all convert.I was leading tech already and income was never an issue so never found a reason to go low piety.
Zero PUs were formed by me or anyone really, which is really a shame as it helps me alot if say Austria gets Hungary or Castile/Spain gets Aragon.Crimea I allied early on but still kept their expansion in check by warring their allies (they allied the Mamluks even) and forcing them to release anything they got so could have an easier time vassalising later.Basically make sure they don't expand past their initial borders or if they do, just dow their ally and seperate peace them but try to not take the territory yourself or if you do remove their cores on it in a war after.You can indirectly help another horde like the Golden Horde to beat them so they take their border, they will still like you and will be small enough to vassalise, after that, just feed them back whatever they lost.
For expanding into the hordes its the same vassal feeding trick, ally/diplo vassal whichever horde got hit hard and small enough to vassalise, then get them their cores back, force the big hordes to release whatever they annexed and vassalise that aswell till every horde is small enough to be vassalised and yeah, always try to expand somewhere, if you got truces in the east check what you can get in the west meanwhile, but you won't be able to do much in europe after 1600, not efficently anyway so keep that in mind.You should also try to avoid getting coalitions against you in the east, you really don't want to be forced to do nothing for 5 years, always try to use the return territory peace deals for your vassals to skip AE generation, don't worry about needing to split your armys, I could fight in 4 fronts if needed against the asian powers, just have a decent sized army (30-40k) at the main theaters for wars/rebels and your fine, noone will even remotly stand a chance so might aswell keep most of your troops in europe/north africa.
oh and don't bother allying any european power, even France is pointless, they will only get you into pointless wars, the only thing diplo relation slots should be reserved for is vassals or to be vassals, don't be afraid to go over your diplo relation limit as long as you get atleast 6-7 DIP a month