You can get a 5HI/1LI ancient rush going by 3:20 on a small map (larger than you would normally rush on) from one barracks.
Go Sci1, make 3 citizens to fill lumber, take one citizen and move it towards the enemy cap and then plot your scout. The citizen you ordered off will take at least a minute to get close to the enemy border, in this time you should be able to fill your lumber and make more citizens to scout the corner/edges/rest of map for ruins.
It's important that you manipulate your ruins to food, you can take one, possibly two wood. It's quite easy to achieve this, as soon as your food gets to 108 then you can research Mil1 which will kill your food.
As you have no need for wood, by the time your citizen reaches the enemy border, you should have a couple of hundred so slap a barracks down on the border. While this is building, keep making more citizens to scout for ruins. Your food needs to be kept between 50 and 100, sadly this means that you will most likely pick up an unwanted wealth ruin unless you are very quick on the resource manipulation. ie, spot a ruin on the map and hit cV to deplete your food, then cancel the citizens when you get the food ruin.
Once your barracks is built, around 2 mins, just put HI on infinity queue and scout with the builder for more ruins. You can scout any near black spots with the first 2 HI and have them return to the barracks by the time the next 2 come out. You will also probably need 1LI too.
Around about just after 3 mins you should have a force of 4-5HI/1LI assembled on the border of your enemy, it may even be burning inside if he went civic. Set the rally-point of the barracks on the enemy cap and send them in. A couple of games I had against toughest AI, I damaged cap at 3:20, the main problem is the time it takes the builder to walk across the map, but I use this time well by booming my economy before researching Military. only Lakota can do this sci1/mil1 build because of the unique way they boom.
I wonder how many people expect a boomed ancient rush by 3:20 from Lakota