How to Defend Against the Turk Rush?

Consider this scenario: Team game on Black Forest, you are at the middle of Castle Age, placed all your extra Town Centers, making farms, booming etc.. You only have 1-2 of each military building, and boom (!) it's the Imperial Turks! 5-10 Bombard Cannons and 20-30 Janissaries. They already took your wall down, they are inside.. Already building offensive castles and towers.. What do you do?

I always try to pump as many Skirms as possible, and make Scout Cavalry to get to the BCs quickly. The SC are instantly killed by Janissaries/HCs. Skirms are killed by BCs.. I also try to add rams and mangonels to the mix. Rams as meatshield to Janissaries, onagers to take them out..

While I'm considering my next move, the BC's already took down all my military buildings, it's basically gg, unless three teammates come to help me..

So.. how can I defend against such a rush? Note that I'm not even Imperial yet! I don't have that great an eco yet. No idea how the opponent did a fast imp and massed an army so quickly..

What would you do in this case?

Notes:

I play HD, Black Forest team games. I'm usually good with eco, if they let me boom that is.. I usually play with defensive/siege civs such as Teutons and Koreans. At this point I have almost no technologies researched so I'm any generic civ. Would appreciate ideas if any civ is advantageous against such a rush, I will just go that civ if an opponent is Turks.

I know the best strategy against Turks is to rush them and not let them get to the Imperial Age, but let's say we are already past that point.. How do you counter this rush?

Thanks