Europe:
Bandits (All regions):
Mercenary Serjeants (Western & Central Europe):
Almogavares (Iberia & Greece):
Highlanders (Scotland):
Gallóglaigh (Scotland & Ireland):
Robber Barons (Western & Central Europe):
Crusaders:
Religious Fanatics:
Crusader Serjeants:
Great Cross:
Middle East & Africa:
'Ayyārūn (Syria, Egypt, & Persia):
'Rukban (Arabia & Africa):
Maghrebis (Arabia & Africa):
Jihadists:
Mutatawwi'a:
Mujāhidīn:
Gāzī:
Asia:
Yóuxiá (China):
Bohai (Korea & Manchuria):
Steppes:
Sibiryaki (Siberia):
Steppe Clansmen (Pretty much the entire steppe):
Steppe Nomads (Pretty much the entire steppe):
Kunok (Cumania and Hungary):
Kazaki (Caucasian Steppes & Siberia):
Promyshlenniki (Caucasian Steppes & Siberia):
More to come!