April 11, 1921: Britain gives 75% of Palestine to Saudi Emir
April 11, 1921: Britain recognises Saudi Emir Abdullah's rule over 3 provinces of Eastern Palestine, officially ceding 75% of the Mandate. Britain retains the "Mandate in Palestine" over the 1/4 of the land that lies to the west of the Jordan river.
Information regarding this can be found on the Jordanian government website, http://www.kinghussein.gov.jo/his_transjordan.html