Movement of Money among States
It is self-evident that when individuals of one state move to another, they bring with them some quantity of currency.
A traveller who visits a foreign state purchases those things he needs for his sustenance while abroad, and perhaps other goods to bring back, is consuming the goods of one state in exchange for the currency of another.
A laborer who visits a foreign state to work removes his labor from his own nation and perhaps some amount of currency he has saved. If he works in the foreign state for some time and sends some part of his wages home to support his family or estate, this creates an ongoing movement of currency among states.
A landowner who chooses to reside in a foreign state, while maintaining his lands an continuing to work them, represents a more sizable and ongoing movement of money from one state to another.
The same can be said of merchants whose activity involves moving merchandise from one state to another and carrying back the money for which it was sold.
A state, like any citizen, can upon receiving capital from whatever source either spend it and thereby put it into circulation, or set it aside in a hoard to be spent later, presuming it can be spent later, and remove its value from circulation until such time it is spent out.