I played from the start of the MA again, and got Chivalry 12 turns earlier, in 400AD, against 520AD in our real game. We also have 35 horses at that time, just we have a small cash problem, but then in this quick game I didn't build galleys or even do any trading as I just wanted to see how quickly we could have got it.
At this period in the real game, we launched more attacks with horses as we were still a long way from Chivalry, getting to Chivalry in 400AD there would have been no need to do that and we would surely have had better success with the attacks on England/France.
Smackster