“Chaldeans.” Strictly speaking, “Chaldea” (sometimes “Chaldaea”) was the area on the north-west end of the Persian gulf, but especially since a number of Babylonian kings came from Chaldea, the name “Chaldea” was often used for the whole of Babylonia, and that is the case in Habakkuk.
“who march through the width of the earth.” This is a hyperbole, but the conquest of the Babylonians did cover much of the known world at that time.