Monkey soldiers were a race of flying monkeys Dorothy encountered in Oz.
Background[]
Those creatures, were only bound to serve the witch there three times, a much different than their counterparts in Daventry, another race of Monkey soldiers known as goons.[1] The flying monkeys were sent out by the wicked witch to chase Dorothy and capture her.
Derek Karlavaegen drew more literal monkey-like soldiers a map of Tamir. He drew them during his own visits and experiences to the land, and/or based on writings of Valanice (who recorded Rosella's story) from the Chronicles of Daventry, which mentions flying monkeys as well (but also refers to them as 'goons')[2]. This species apparently from Oz, but withdrew to the world of Daventry have four monkey legs, a tail, and bat-like wings.
They and the more familiar goons offered their help to Edgar while he still remained in Tamir.
Behind the scenes[]
The monkey soldiers are a reference to the monkey soldiers under the "Wicked Witch of the West" in the Oz books.