One of the things it took me a while to get my head around was that there kinda was no overarching nation at the time in question - at least not in the way we think of it today. The Ottoman Empire was defunct; nominally there were laws of the nation, but it was in no position to enforce them, and many of them hadn't been popular anyway (as they were secularizing).
In practice the people in the area operated as 'millets' - micronations unified by religious belief, governing themselves according to religious law. When the British took over administration of the region in 1917, they didn't try to change this.
So for the most part, the landowners that the Jewish Agency was buying from were the governance. The trade wasn't like one citizen of a nation selling to another citizen of the nation; it was like one country selling land to another country (and so moving its borders).
In practice the people in the area operated as 'millets' - micronations unified by religious belief, governing themselves according to religious law. When the British took over administration of the region in 1917, they didn't try to change this.
So for the most part, the landowners that the Jewish Agency was buying from were the governance. The trade wasn't like one citizen of a nation selling to another citizen of the nation; it was like one country selling land to another country (and so moving its borders).