I ended up rushing two more pikes in Gandasetaigon, which made for 2 pikes and an elite spear there. That apparently changed the AI's calculation and the Mongols started landing on Main Island again in 800 AD. Cool - target practice. Actually, not so cool, I'd been shipping so many units to Bapedi Island, I had little on hand to take care of the landing - no catapults at all, for instance. Plus, most of Main Island defenders are spears or even warriors serving as MP. A two-unit landing won't get a city but it can be a problem. I start measures to take care of this, but the focus is still on the landing on Zulu Mountain.
800 AD also sees a minor milestone - 20 pikes in Kiohero, only 10 more to go. When that one is en route, I'll rename him so I know when he gets to Kiohero without counting. It's getting rough to see all the units there. I also take my single galley over by the Eastern Islands (north of Arabia) and load up a MW and a settler and head for Southeast Island past Arabia. Worst case, I'll just have to abandon the city. It's a gamble, but it only costs me some gold.
The trap on North Island is also getting me some more elites against Zulu and Egyptian foes. The ships I'd sunk earlier though is telling, as not many units land. And they often sail around to random locations on the back side of North Island to drop off troops. I'm fully roaded, so it's not a big deal (as long as they don't coordinate too many landings on the same turn) to me, but it's longer sailing time for them. Whatever.
I lose a MW attacking Mongols on Main Island in 840 and actually get attacked. OK, it was a 2 hp horse and he promptly died, but it convinced me to get serious about defending Main Island a bit better. A couple MDI and some 'pults will do the trick.
It's only a bit later, 850 AD, that I'm ready to start the invasion of Zulu Mountain. I load up 18 pikes and 2 archers as wave 1 and move them up to Zulu Mountain. No boat attacks, please, AI. Thank you.
I unload wave 1 in 860 AD and head back where wave 2 (12 pikes and 8 archers) load up. I check F3, too, and find my army (190 units) is now average vs. Egypt. Good news! My 200 unit estimate was probably close. Still, there's extreme trepidation. What's the interturn going to show? How many attacks will the AI make? Will I survive this? Were my calculations correct?
In minor news, Skannayutenate is founded on Southeast Island.
With adrenaline pumping, I press enter and await the interturn.
..
..
..
And nothing happens. NOTHING! No attacks at all. Zulu Mountain is left alone. WTH? Did the Zulu have no attack units? Are the Egyptians coming and just didn't make it into visible range? What?
Oh, wait, something did happen. The Japanese formed Nara on Southeast Island. That location might be a challenge.
I go ahead and drop off wave 2 on Zulu Mountain in 870 AD. I mean, what else is there to do? It can't hurt to have more troops in place. That gives me my full 40 units on ZM. If the Egyptian waves do come, I'm ready. The initial 18 pike fortify, too, to give them added defense against the hordes I expect to see coming any minute now.
But, no. The Egyptians and Zulu stay passive. Nothing on the interturn. Nothing appears. Boats continue to pester my other holdings, but the big action at ZM is turning out to be a big dud. Will the AI not attack at those odds? Must be.
Oh, and Nara is defended by an archer, visibly. I have a vet MW. Odds will be in my favor next turn.
I don't have to decide on the Zulu front in 880 AD. My ships simply retreat and the rest of the pikes fortify. I'm in good position now. But what to do? Will the AI simply not attack a huge stack? Defense 3? Is it the mountain? I dunno.
Attack Nara, though. I do one damage to the archer, yellow-lining it and retreat. Hmmm... Lots of culture-free area where I can rest and heal, at least.
The 880 AD interturn is interesting, though. No, not attacks on Zulu Mountain. That'd be sweet at this point. No. Monotheism pops from the Great Library. And then Engineering pops, too (Egypt and Zulu apparently traded). I had only 5 turns left on my min run on Engineering. Wouldn't an SGL have been interesting?

The fun doesn't stop there, though, as New York completes Sistine Chapel. Every time I see more stuff from America, I fear them more. Everybody else is dangerous, too, of course, but America is easily the scariest. I just can't do anything about them right now.
Well, if the AI is going to ignore me at ZM, I'll just ignore them, too. Load up another 20 units - pults and MDI and swords and even another couple pikes. We'll land by Zimb and move in everybody off ZM and see what they think of that!
Also, I stop producing units. Well, almost stop. A couple of corrupt outlying towns still work on a couple units, but essentially every single non-corrupt town (really only 10 of them) start building cathedrals. I want to drop my lux tax to 20% (or even 10% but I don't think that will be possible). 2 cost for 3 happy faces is a good deal. And it might be necessary to prevent a culture win later in the game. Some culture can only be a good thing, especially when it helps in other ways.
890 is as expected, nothing happens.
Something WILL happen in 900. I put 58 troops by Zimbabwe on the desert. Ignore me at your own peril! I also see another Japanese ship by Southeast Island. Skannay may have to be abandoned. My MW is still healing up by Nara.
Status:
Zulu - 2 cities - UP Invention - my mil is strong
Egypt - 4 cities - par - my mil is average
China - 4 cities - down Literature, Currency - my mil is average
America - 10 cities - UP Theology, Chivalry. Down Engineering - my mil is weak
Japan - 7 cities - down Literature, Currency - my mil is weak
Arabia - 8 cities - down Literature, Currency, Republic - my mil is average
Mongols - 7 cities - down Literature, Monotheism, Fuedalism, Engineering - my mil is weak
Yeah, the 900 AD AI turn is a bit longer and more entertaining. Egypt still can't reach me, but I see at least 40 fast-movers (war chariots and horsemen) come barreling down at me. There are probably close to that many that move that I didn't see with my single spotter. Zulu move, too, and attack my stack with 3 archers. All 3 die to my pikes, doing 1, 2, and 3 damage.
OK, they won't stand for me on flatlands. Fair enough. 'Pults go back on boats (except the elite, which stays empty to protect the fleet). Everybody else goes back to Zulu Mountain. I call this OPERATION RETREAT. As Zaphod Beeblebrox says, "Discretion is the better part of valor. And cowardice is the better part of discretion." So I valiantly beat a retreat. Once they're locked in, will the AI continue to target?
No, they retreat. Spotter ship sees the Egyptian hordes race back to their territory. Cool. The AI is so predictable. The Zulu do attack and sink an empty boat. Good thing I generally protect my fleets with more boats.
So, in 920 AD, I move back off Zulu Mountain onto the desert. What's changed? Notice how I said I only had 58 units last time. I'd kept a boat in reserve by Kiohero. It loaded up properly and adds a couple units to the stack. The important one is a settler (the other was a worker, but growing the city/disbanding the worker for shields didn't really work out). I'm gonna have at least one round of attacks on my stack without walls on flatlands and that will be scary and painful. On the plus side, I'll get to heal between waves of attacks and will have walls very soon.
During the interturn, the Egyptians swarm as expected, the Zulu can't even muster a single archer to attack the stack. And the Japanese land an archer/spear pair by undefended Skannay. Plus, they got a spear in Nara, so the archer comes out to play with my MW.
I do the boring stuff first in 930. I attack an archer by Nara and my MW gets its revenge by killing the guy flawlessly. He of course retreats to a safe distance! Skannay gets abandoned. It had grown to size 2, but there was no way to save it. I quote both MacArthur and The Terminator to cover my bases and continue on with other plans. I have a couple shiploads of stuff from Eastern Island that I want to ship, but ships are rather busy at the moment!
Onnontare is founded on Zulu/Egypt island. It rushes a worker and then changes its mind and rushes walls (120 gold). The 43 visible attackers will be able to attack without walls, on flatlands. Pikes fortify out the yang. The catapults sing, trying to damage some Zulu roads, to slow the hordes just a bit, so that I can defend behind walls instead of a tiny town just recently built in the desert! But they fail. Apparently, damaging roads is beyond the capability of a catapult...
There's some fairly intense cultural pressure and I'm inordinately close to Zimbabwe, the Zulu capital. But I actually have more culture than Zululand and 50+ military units is a good reason to not flip.
Of course, it's the units arrayed against me that are a bigger concern. This is just one stack....