Perry Miniatures Historical Range - they also have a wonderful Korean range
The Assault Group Medieval Asia Range
Grenadier (now available from a variety of suppliers) have Samurai Orcs (!), and steppe riders
Reaper have so many miniatures that the best thing to do is use their search function: terms like "ninja", "samurai", "oriental" etc turn up good stuff, including the funky new Pathfinder mini of Ameiko - perfect for a wandering minstrel.