Oh! I just investigated the Arabs and they are 100% coastal and only have 6-7 troops per city. This could be very interesting, very quickly.
Edit: I think I am formulating a plan. We are at about 11% of the territory. Mongols @ 31% so I can do this without taking on Khan, but I risk cultural loss if it takes too long. Japan is isolated and 6% of the territory, with 50+ units in each of their cities and would tie down a huge invasion force, the Zulus are 2-3% of the territory and next to the Mongols. I don't think they are going to survive much longer.
So 4 phases to the plans:
Phase 1: Try to wipe out the Arabs in 4-5 turns with Zerk rushes. Will take 45-50 Zerks + 18 Caravels. I've got the Caravels, and I'm probably 10 Zerks short, so I can do this soon. Gift cities to the Zulus, then take them all back in a couple of turns. Arabs are another 8% or so of the land. That gets me up to 19% or so, and I'm #2 on the board and I pick up another lux. But no horses still. Pray for an MGL.
Phase 2: Have the Egyptians go to war with America, pulling troops out of all of the American cities. Zerk rush the Americans who have fewer units in their cities. Gift again to the (near dead) Zulu, war to take it back. I will have to have an MGL by the end of this phase. I hope to get 90% of the American cities, another 8% of the territory, up to 25-27%.
Phase 3: I should have an MGL and horses for Cavalry Armies. If I don't have Armies, then Phase 3 has to be to do island Zerk rushes on the Mongol islands to pick up another 15-20% of the territory and hold and hope for an MGL. I don't love this option, but it should be effective. If I do have Armies, I think I take out the Egyptians by Zerking their islands and "poofing" their army on the mainland. That's probably another 12-15%, getting me up to 42% or so.
Phase 4: Mongol war. Phase 4(a) Zerk all of the island Mongol cities. We should be over 60% by the time I take their all of their islands. Phase 4(b) Land Mongol mainland with Armies and Artillery and raze + replace to get to 66%. Japan survives untouched, and a rump Mongol state survives, and whatever is left of Zululand (already down to just 3 cities) survives.