Jordanian annexation of the West Bank
The Jordanian administration of the West Bank officially began on 24 April 1950, and ended with the decision to sever ties on 31 July 1988. The period started during the 1948 Arab–Israeli War, when Transjordan occupied and subsequently annexed the portion of Mandatory Palestine that became known as the West Bank, including East Jerusalem.
Source: Wikipedia — Jordanian annexation of the West Bank (CC BY-SA 4.0)