Thanks, I traced the contour lines over a much lower quality contour map; it actually doesn't take too long. Makes for a much nicer looking physical map, akin to the original Diplomacy board: http://imgur.com/a/U9X9q (Pretty easy and cheap to make, nice for pushing armies around.)

I thought about a "barbarian" power in the north. Although I'm far from an expert, it sounded to me like the barbarian powers were much less powerful, and I thought it was nice to keep it to the main warring states. The Huns are there in spirit: Xiongnu is the Chinese term for them.

Wei is definitely in an interesting spot. They do have the "shortest" path to victory though (2.13 spaces to 18 centres from all home centres), and access to the two main clusters of centres, plus a possible supported move into Ye on the first turn. The wall in Daliang should discourage a casual opportunistic attack from Han and so enhance trust. I gave Han a wall in Luoyang to enhance its defense as well, and the wall in Anyi to help it out as well, plus access to the same two clusters of centres. I'm hoping an extra unit isn't necessary, but it's a possibility.

There are some centres outside the two main clusters, true. I think of Jiuyuan and Shang as Spain and Portugal. Ba and Danyang are like Tunis. Although Ba is on a river that leads into Chu. The extra space around Chu makes it a safe but slower start, and gives the more pressed countries a head start on more centres.

Obviously a lot of the balance decisions require playtesting; I'll certainly let you know if I ever get a game going.

Some more "distances to 18":

Qin 3.22
Chu 3.00
Zhou 2.71
Wei 2.13
Han 3.00
Yan 3.57
Qi 2.63

Centres within 3 that are enemy home centres, and % of all centres within 3:

Qin 5 31%
Chu 8 44%
Zhou 8 40%
Wei 11 44%
Han 7 39%
Yan 6 43%
Qi 10 48%