In China the most popular is donkey meat, or 驴肉 (lvrou, pronounced lew-row*). For those who don't study characters, the left-hand part of 驴 is 马 ( horse), which is the simplified form of the traditional character 馬 which is what the Japanese are still using, and has a reconstructed proto Sino-Caucasian root.[0] It's all over China but more popular perhaps in the north, Shandong and northern Jiangsu in the east to Xinjiang in the west. Of course part of this culinary capacity descends from earlier nomadic and steppe peoples. You can also try Mongol horse milk alcohol, which is now available right across China in bottled form.
I think it's fair to say that in the past, most people ate most meat, as long as it was fresh and there were no local taboos. I haven't read any studies but for bacterial reasons I suppose that raw consumption correlates with cold climates.
If you go back to Japan, I highly recommend trying it. It is one of my favourite foods. Horse meat has a nicer flavour than beef, and especially eaten raw it is amazing. Unfortunately horse meat is quite rare where I live (Shizuoka prefecture), so I only usually get to eat it when I'm travelling.
I often wonder where the meat comes from though. Do they use young horses, or old, for instance? Also, the basashi I've had seems like it might be the tenderloin (it is very tender), so I wonder what happens to the rest of the animal. I'd very happily use it in stews if I could get it.
In fact here's a search for places using the term 馬刺 [basashi] (馬=horse, 刺=from sashimi
Lots of places come up specializing in it
http://s.tabelog.com/smartphone/restaurant_list/list/?utf8=%...