1 and 2 Kingdoms are equivalent to 1 and 2 Samuel, and 3 and 4 Kingdoms are equivalent to 1 and 2 Kings in most modern English versions.
[1] These books are known in the Vulgate version as the four Books of the Kingdoms (Libri Regnum or Regnorum),[1] or the Book of Kings (Liber Regum) as Jerome disagreed with the expression Books of the Kingdoms (Libri Regnorum) of the LXX.
[2][3] Jerome says: Third comes Samuel, which we call the first and second Kings.
It is much better to say Malachim, of kings, than Malachoth, of kingdoms.
For it does not describe the kingdoms of many peoples but of one Israelite people which included twelve tribes.