Horsebows

Horsebows are a short traditional bow designed to be shot from horseback. Their usage goes back as far as humans have used both bows and horses> Because of their size many horse bow archers would also use thumb rings, however straight off the fingers is also quite common. 
These bow can also be shot from a standing position, so don't worry, you don't need to buy a horse as well. 

If you do what to get into horseback archery here is an Australia website on getting started. 

https://www.horsearcheryaustralia.com.au/horse-archery