Have you tried advanced world gen? I could let it run up to 300 every time with a ''stop at 15% of megabeasts'' dead.
This was on a very large region with tons of beasts,titans and other ''fun''
Historical beings alive in that world, in year 302[I started in 300, abandoned, redid my legend viewer and these are the stats from that check]
Alive: 17532
Human: 6164
Elf: 5831
Goblin: 2227
Forgotten Beast: 867
Dwarf: 707
Kobold: 325
Minotaur: 179
Titan: 147
Giant: 146
Cyclops: 142
Ettin: 133
Dragon: 109
Bird Roc: 108
Colossus Bronze: 102
Hydra: 59
Yeti: 56
Night Creature: 53
Giant Dingo: 29
Leopard Giant: 21
Troll: 18
: 14
Jaguar Giant: 13
Ogre: 12
Crocodile Saltwater: 11
Alligator: 10
Bear Polar: 9
Dingo Man: 4
Lion Giant: 4
Harpy: 3
Wolf: 3
Rodent Man: 3
Demon: 2
Bear Grizzly: 2
Tiger Giant: 2
Dingo: 2
Imp Fire: 1
Wombat: 1
Green Tree Frog: 1
Bird Swallow Cave: 1
Troglodyte: 1
Gorlak: 1
Blendec Foul: 1
Scorpion Desert Giant: 1
Beak Dog: 1
Bear Black: 1
Leopard: 1
Cougar: 1
Cave Swallow Man: 1
Donkey: 1
Water Buffalo: 1
site population shows a shitload of titans around that probably havn't gotten themselves listed as historical figures yet.
Site Populations: 1235343
Cave Swallows: 296002
Bats: 293108
Goblins: 232924
Cave Spiders: 174607
Elves: 84307
Humans: 68416
Dwarves: 10846
Dogs: 9049
Cats: 8058
Donkeys: 5335
Mules: 5333
Yaks: 5165
Horses: 4588
Water Buffalos: 4451
Kobolds: 3985
Reindeers: 3055
Rabbits: 2729
Cavies: 2366
Geeses: 1605
Alpacas: 1523
Guineafowls: 1403
Cows: 1324
Turkeys: 1282
Goats: 1233
Pigs: 1169
Ducks: 1051
Chickens: 937
Blue Peafowls: 935
Sheeps: 835
Trolls: 825
Human Outcasts: 649
Llamas: 615
Gorlaks: 549
Animated Humans: 500
Troglodytes: 394
Naked Mole Dogs: 312
Giant Moles: 295
Goblin Outcasts: 281
Large Rats: 263
Giant Rats: 249
Kobold Outcasts: 179
Minotaur Outcasts: 179
Animated Goblins: 176
Giant Outcasts: 146
Gremlins: 143
Cyclops Outcasts: 142
Giant Cave Swallows: 140
Giant Bats: 138
Ettin Outcasts: 133
Elk Birds: 131
Dragon Outcasts: 109
Roc Outcasts: 108
Bronze Colossus Outcasts: 102
Elf Outcasts: 100
Dralthas: 81
Helmet Snakes: 62
Hydra Outcasts: 59
Yeti Outcasts: 56
Animated Elves: 51
Giant Earthworms: 43
Rodent Man Outcasts: 37
Elf Prisoners: 37
Hill Titan Outcasts: 31
Giant Dingo Outcasts: 29
Dwarf Outcasts: 29
Drunians: 21
Giant Leopard Outcasts: 21
Forest Titan Outcasts: 21
Troll Outcasts: 18
Desert Titan Outcasts: 18
Blind Cave Bears: 16
Marsh Titan Outcasts: 14
Giant Jaguar Outcasts: 13
Cave Swallow Man Outcasts: 12
Ogre Outcasts: 12
Saltwater Crocodile Outcasts: 11
Alligator Outcasts: 10
Brush Titan Outcasts: 10
Plains Titan Outcasts: 10
Polar Bear Outcasts: 9
Swamp Titan Outcasts: 9
Lumbering Horror Outcasts: 8
Freaks of Twilight Outcasts: 8
Savanna Titan Outcasts: 8
Tundra Titan Outcasts: 8
Lumbering Creature Outcasts: 7
Mountain Titan Outcasts: 7
Human Prisoners: 6
Dark Hag Outcasts: 6
Glacier Titan Outcasts: 6
Dingo Man Outcasts: 4
Giant Lion Outcasts: 4
Bellowing Monster Outcasts: 4
Wolf Outcasts: 3
Harpy Outcasts: 3
Dingo Outcasts: 2
Giant Tiger Outcasts: 2
Grizzly Bear Outcasts: 2
Freaks of Twilight Outcast: 2
Women of Evil Outcasts: 2
Sand Titan Outcasts: 2
Jungle Titan Outcasts: 2
Iguana Devils: 1
Skink Fiends: 1
Donkey Outcasts: 1
Beak Dog Outcasts: 1
Dwarf Prisoners: 1
Water Buffalo Outcasts: 1
Cougar Outcasts: 1
Leopard Outcasts: 1
Black Bear Outcasts: 1
Giant Desert Scorpion Outcasts: 1
Foul Blendec Outcasts: 1
Moon Horror Outcasts: 1
Monsters of Evil Outcast: 1
Wicked Troll Outcasts: 1
Midnight Troll Outcasts: 1
Midnight Freak Outcasts: 1
Winged Troll Outcasts: 1
Brutes of Evil Outcast: 1
Gloom Troll Outcasts: 1
Monsters of the Night Outcast: 1
Moon Freak Outcasts: 1
Emaciated Creature Outcasts: 1
Gloom Freak Outcasts: 1
Twilight Horror Outcasts: 1
Skinless Freak Outcasts: 1
Creatures of Twilight Outcast: 1
Narrow Freak Outcasts: 1
Taiga Titan Outcasts: 1
The world had 6 towers, so I caged 7 necromancers in the first two years for science!
tl;dr : it's not that hard to get a world full of fun with advanced world gen, have you tried playing with that tool?