-Marley
-Eldians - the true King/Paradis Island
-Eldians - under Marley control
-Eldians - Tybur Family.
What I suspect it really happened is the following: it wasn't normal humans/Marleyans the ones that defeated the Titans, that's propaganda, again. Eldians were surely divided in small kingdoms/warring factions, with each shift Titan being the leader of each one. Maybe Hisayama thought something like the Sengoku period?
Wars between them were normal, and that has been going for hundreds of years. But 100 years ago, a bigger war than normal between Eldians happened, and finally it won one faction, the Tybur family. The biggest opposing faction retreated to the island (or maybe it's true they were fed up of so much war), and the smaller, defeated titan kingdoms were subjugated and given to the underlings of Tybor, the Marleyans.